Porphyrin Chemistry

A straightforward condensation method has been employed to introduce the potential alternative anchoring group of vanillin in porphyrins. Depending on the number of carboxylate groups in the porphyrin ring, the electrochemical and optical properties were studied. A slight hypsochromic shift was observed when the number of carboxylate groups in porphyrins increased in the emission and absorption bands. Calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels from cyclic and differential pulsed voltammogram studies clearly indicate that the LUMO energy levels of the dyes vary significantly with the number of carboxylate groups. It improves the electron injection dynamics of porphyrin-sensitized solar cell devices, offering them to achieve 0.36% PCE in PC-3 dye. Additionally, the recombination kinetics, denoted by τ rec and k rec , which are also affected by the carboxylate group, was calculated using the transient photovoltage decay. This demonstrates that the process of recombination at vanillin-anchored porphyrin dyes with carboxylate groups occurs very slowly.

A convenient reaction protocol has been explored for the synthesis of A 3 B-type meso substituted porphyrins containing three thien-2 0-yl groups and one subsituted phenyl group. 100-150 mg of pure A 3 B thienyl porphyrins was obtained from a single reaction in the case of 4-hydroxyphenyl, 3-nitrophenyl, 3,4,5-trimethoxyphenyl, 3,4-dimethoxyphenyl and 4-pyridyl substituents. NMR, UV-vis, fluorescence and electrochemical studies were conducted using pure products to understand the effect of the nature of the meso phenyl group on the electronic properties. X-ray structural analysis of thienyl porphyrins containing 4-hydroxyphenyl and 3,4,5-trimethoxyphenyl residues confirmed the substituent regiochemistry and the conformations of the thienyl groups in the solid state. The UV-vis and fluorescence bands experienced modest blue shifts when compared to meso-tetrathien-2 0-yl porphyrin (H 2 T-2 0-TP). The redox potentials showed cathodic shifts with respect to H 2 T-2 0-TP and revealed variation of frontier orbital energy levels depending upon the phenyl substituent. Computational DFT and TD-DFT studies on all the phenyl derivatives confirmed the role of the phenyl substituent in modulating the HOMO and LUMO energy levels and agree well with the observed effects of the optical bands and the redox potentials.

For developing efficient DSCs, anchoring moieties need to be understood in detail with respect to a particular dye. Herein, we have synthesized new Zn-thienyl porphyrin dyes based on pyridyl and hydroxyphenyl anchors and compared with traditional carboxyphenyl anchoring group. The effect of such variation in anchoring groups was investigated with UV-vis and fluorescence spectroscopy as well as electrochemical studies. The hydroxyphenyl appended dye showed higher molar extinction coefficient and red shifted emission bands. Both pyridyl and hydroxyphenyl dyes showed adsorption over TiO 2 semiconductor. The dye loading amount was found to be greater for carboxyphenyl dye due to stronger bidendate coordination of the carboxy group, as revealed by FT-IR studies. The electrochemical potentials were found to be strongly influenced by the anchoring functionality and all the dyes showed positive driving force for electron injection to the conduction band of TiO 2 and regeneration of oxidized dye by the redox electrolyte. DSC devices were fabricated for each of the dyes and characterized well. Hydroxyphenyl dye showed higher V oc as a result of lower back reactions. Transient photovoltage decay measurments indicated lower recombination rate in hydroxyphenyl and pyridyl than the carboxyphenyl anchored thienyl porphyrins offering potential for further dye optimization.

An anchoring group is necessary for linking dye and photoanode as an array. The inter-electron transfer between the layers produces the photoelectron when it is exciting. The introduction of a novel 3-methyl-4-hydroxy phenyl anchoring group to the porphyrin periphery and its potential use in organic solar cell (OSC) applications were addressed. The bare dyes are soaked with a titania aerogel photoanode. FT-IR, UV-visible, and CV spectral analyses further study the electron transfer mechanism at the TA/dye interfaces. The 3-methyl-4-hydroxy phenyl anchor's two attachment points to the titania aerogel (TA) surface were validated by FT-IR at 1630 and 1400 cm-1. The spectrum broadening and band shift after TA adsorption show the dyes' electronic coupling and aggregation features. In order to provide more insights into the kinetics of electron transfer, the exact HOMO and LUMO energy levels are estimated, and the energy level diagram compares the conductance of TA and electrolyte potential. The 3-methyl-4-hydroxy phenyl anchor was used to demonstrate the ability of the dye/TA photoanode to generate an electrical current as an OSC device. The effects of the subsequent change in photocurrent on the number of anchoring groups in the metal-free porphyrin system are studied.

Two new Zn(II) porphyrin dyes ZnNPCA and ZnNPHy bearing three naphthyl groups and one carboxyphenyl/hydroxyphenyl anchoring group in an A 3 B meso substitution pattern was synthesized utilizing a mixed condensation approach. The redshifted absorption bands to 427 nm as impacts on the extended conjugation with three naphthyl substituents. Similarly, the emission spectrum also exhibits a redshift than ZnTPP-COOH dye. The anodic shift was found in the reduction potential of the naphthyl dyes with the carboxylic acid anchor (ZnNPCA) , facilitating the more favourable electron injection. Moreover, the naphthyl porphyrin dyes positively interacted with semiconducting TiO 2 , whose binding mode was further established using FT-IR. While interacting with titania, the more broadening absorption spectra exhibit strong electronic coupling and will benefit the electron injection. The high dye loading amount obtained for ZnNPCA dye was 13.1 × 10-8 mol cm 2 , which is more significant towards light harvesting. DSSC devices were fabricated using porphyrin-sensitized photoanodes. ZnNPCA showed better efficiency than ZnNPHy owing to higher dye loading onto the titania surface. Furthermore, the influence of coadsorbent DCA on the photovoltaic performance of the fabricated DSSC devices was investigated. As a result, a maximum efficiency of 1.85% was achieved for ZnNPCA/DCA device. In addition, electrochemical impedance spectroscopy results revealed a higher electron lifetime (6.14 ms) for this device, supporting better suppression of back reactions.

Photoremovable protecting groups (PPGs) represent one of the main contemporary implementations of photochemistry in diverse fields of research and practical applications. For the past half century, organic and metal-complex PPGs were considered mutually exclusive classes, each of which provided unique sets of physical and chemical properties thanks to their distinctive structures. Here, we introduce the meso-methylporphyrin group as a prototype hybrid-class PPG that unites traditionally exclusive elements of organic and metalcomplex PPGs within a single structure. We show that the porphyrin scaffold allows extensive modularity by functional separation of the metal-binding chromophore and up to four sites of leaving group release. The insertion of metal ions can be used to tune their spectroscopic, photochemical, and biological properties. We provide a detailed description of the photoreaction mechanism studied by steady-state and transient absorption spectroscopies and quantum-chemical calculations. Our approach applied herein could facilitate access to a hitherto untapped chemical space of potential PPG scaffolds.

Porphyria refers to a group of rare metabolic disorders arising from defects in the heme biosynthesis pathway. This paper provides an introduction to porphyria, detailing its pathogenesis, diagnosis, and essential laboratory tests. Key diagnostic tools, including plasma scans, fluorocyte analysis, and the Hoesch test, are described alongside their significance in confirming porphyrinuria. The classification of porphyrinuria, its chief signs and symptoms, and a simple laboratory test for porphyrinuria are discussed to emphasize clinical and diagnostic Porphyria: An Overview of Pathogenesis, Diagnosis, and Laboratory Tests Amblest Kanu relevance. The paper serves as a concise guide for understanding the intricate relationship between biochemical pathways and the clinical manifestations of porphyria.

The chemistry of vanadyl porphyrins has been explored using vanadyl octaethylporphyrin as a substance in petroleum porphyrins, crude oils and bitumen. The structural, electronic, thermodynamic, spectroscopic properties are described. The geometry’s optimization of this molecule was done by Density Functional Theory (DFT) using the hybrid Beck three-parameter hybrid functional combined with Lee-Yang-Parr correlation functional (B3LYP) and 6-31G(d) standard basis set. All calculations have been made in the gas phase and in different solvents: benzene, benzonitrile, tetrachloromethane and chloroform. The calculated infrared spectrum was compared with experimental spectroscopic data, and the vibrational assignment was provided. An electron density analysis in terms of natural bond orbitals was conducted to determine the nature of the bonds between the vanadium and nitrogen atoms. The spatial representation of the associated molecular orbitals helped to explain the formation of the V-N b...

A series of meso-substituted with aromatic (=tolyl, pyrenyl,
fluorenyl, naphthyl, and triphenylamine) substituents, platinum
(Pt), and palladium (Pd) porphyrins have been synthesized and
characterized by spectroscopic and single-crystal X-ray diffraction studies to probe structure-reactivity aspects on the electrochemical redox potentials, and phosphorescence quantum
yields and lifetimes. In the X-ray structures, the aromatic mesosubstituents were rotated to some extent from the planarity of
the porphyrin ring to minimize steric hindrance. Both Pt and Pd
porphyrins revealed higher electrochemical redox gaps as
compared to their free-base porphyrin analogs as a result of the
harder oxidation and reduction processes. The ability of both Pt
and Pd porphyrins to generate singlet oxygen was probed by
monitoring the photoluminescence of 1
O2 at 1270 nm. Higher
quantum yields for both triplet sensitizers compared to their
free-base analogs were witnessed. Singlet oxygen quantum
yields close to unity were possible to achieve in the case of Pt
and Pd porphyrins bearing triphenylamine substituents at the
meso-position. The present study brings out the importance of
different meso-substituents on the triplet porphyrin sensitizers
in governing singlet oxygen quantum yields; a key property of
photosensitizers needed for photodynamic therapy, chemical
synthesis, and other pertinent applications.

Porfirinler, bitkiler ve insanlar, ham petrol gibi çok çeşitli yerlerde bulunan karmaşık organik kimyasal bileşikler sınıfındandır. Bazı çeşitleri yarı iletkenlik, ışıldama, fotoiletkenlik, paramanyetizma gibi özelliklere sahipken bir kısmı katalizördür. Biyolojik sistemlerdeki porfirin türevleri ya metal içermemekte ya da demir (hemler), magnezyum (klorofiller), kobalt (B12 vitamini), nikel (kofaktör F430) ve bakır (pigmentler) içermektedir. Bunlardan biri olan klorofil, doğal fotosentez sürecinde, gelen ışığı birçok kompleks basamakla yaklaşık %100 kuantum verimiyle kimyasal enerjiye dönüştürmektedir. Bu bilimsel fenomen, çeşitli disiplinlerden birçok bilim insanına serbest baz veya metaloporfirin türevlerini kapsamlı bir şekilde incelemeleri için ilham vermekte ve vermeye devam etmektedir. Aromatik makrosiklikler oluşturmak üzere dört metiliden (-CH=) köprüsü aracılığıyla birbirine bağlanan konjuge 18 π elektron içeren dört pirolik alt birimden oluşan ve bu sayede özel redoks özelliklerine sahip olan porfirinlerin bu özelliklerinin hibrit nano yapılarda ve nanofiberlerle birleştirilmesiyle çeşitli uygulama alanlarında kullanılabilecek gelişmiş algılama ve enerji depolama özelliklerine sahip yeni malzemeler elde edilebilmektedir. Bu tez kapsamında işlem görmemiş nanofiber ve karbon nanofiberlerin porfirin ile katkılanıp çeşitli yöntemlerle modifiye edilmesiyle (elektroeğirme ile kaplama, Drop Casting (damla döküm)) elektrokimyasal sensör ve hibrit süperkapasitörlere entegre edilebilecek pil tipi elektrot potansiyelinin araştırılması amaçlanmaktadır. Bu amaç doğrultusunda, çalışmanın birinci bölümünde; kafeine duyarlı elektroeğrilmiş poliakrilonitril-(5,10,15,20-tetra(4-tert butilfenil)-porfirin)/karbon keçe elektrot (PAN-Por/CFE) nanofiber elektrokimyasal sensör üretilmiştir. Bu çalışma, elektroeğirme yöntemiyle CFE'nin PAN-Por nanofiber ile kaplanmasıyla basit, geliştirilebilir ve uygun maliyetli elektrokimyasal kafein sensörü için yeni bir yaklaşım sunmaktadır. Bildiğimiz kadarıyla (5,10,15,20-tetra(4-tert bütilfenil)-Por) içeren kafeine duyarlı elektroeğrilmiş elektrokimyasal sensörlerin üretimini kapsayan ilk çalışmadır. PAN-Por/CFE modifiye elektrotu elde etmek için öncelikle PAN-Por öncülleri hazırlanmış ve daha sonra elektroeğirme yoluyla CFE'ye kaplanmıştır. Saf PAN ve farklı oranlarda Por ilave edilerek elde edilen NF'lerin fizikokimyasal karakterizasyonları SEM, FTIR, UV-Vis ve polarizasyon optik mikroskop (POM) teknikleri kullanılarak yapılmıştır. PAN-Por/CFE'nin elektrokimyasal karakterizasyonu ise CV, LSV ve DPV ile gerçekleştirilmiştir. Geliştirilen kafein sensörü için algılama limiti 15–1000 μM doğrusal aralığında 14,06 µM olarak hesaplanmıştır. Ayrıca ölçüm limiti 42,60 µM olarak tanımlanırken, 50 µM kafein için bağıl standart sapma değeri %0,58 olarak hesaplanmıştır. Farklı kahve örneklerinde kafein tespiti için %99,3 ile %102,4 arasında değişen geri kazanım değerleri elde edilmiş ve önerilen yöntem başarıyla uygulanmıştır. Sonraki çalışmada ise PAN-Por nanofiberler elektroeğirme yöntemiyle üretilmiş, karbonize edilip CFE ile modifiye elektrotlar üretilmiş, pil tipi hibrit süperkapasitör elektrot potansiyeli araştırılmış, bunun için fizikokimyasal analizleri SEM, EDS, XRD, FTIR ve POM ile, elektrokimyasal analizleri CV, GCD ve EIS ile yapılmıştır. Yapılan elektrokimyasal analizlerden CV analizinde pil tipi malzemelerin gösterdiği redoks eğrileri gözlenmiş, spesifik kapasitansı 0.5 mV/s tarama hızında 220 F/g olarak hesaplanmış, düşük tarama hızlarında (0.5, 3, 5, 10 mV/s) pil tipi davranış göstermiş, düşük tarama hızlarından alınan verilerle çizilen log tarama hızı-log pik akım grafiğinden b değeri 0.238 olarak bulunmuştur. 'b' değeri belirgin bir difüzyon kontrollü işlemi gösteren bir eğimi ifade etmektedir ve değeri PP2C'nin pil tipi davranışını doğrulamıştır. PP2C/CFE çalışma elektrotu maksimum çalışma voltajına ulaştığında CV analiziyle tutarlılık göstermiş, pil sınıfı şarj depolama mekanizmasını gösteren simetrisi bozulmuş GCD eğrilerini ortaya çıkarmıştır. GCD eğrisinden 0.5 A/g akım yoğunluğunda spesifik kapasitans 177 F/g ve spesifik kapasite değeri yine 0.5 A/g'da 284 mAh/g olarak hesaplanmıştır. 3 A/g akım yoğunluğunda %110.60 ile en yüksek kulombik verime sahip olduğu görülmüştür ancak 4 A/g'da %78.95 değerine düşmüştür. Maksimum enerji yoğunluğu 0.5 A/g akım yoğunluğunda 98.3 Wh/kg ve güç yoğunluğu 348.6 W/kg olarak hesaplanmıştır. Yapılan döngü stabilite testinde 3.5 A/g akım yoğunluğunda 50 şarj-deşarj döngüsü yapılmış, spesifik kapasitansın başlangıç değerinden itibaren %88 civarında artış gösterdiği görülmüştür. Ancak 6 A/g akım yoğunluğunda yapılan 1000 döngülük testte, ilk döngüdeki spesifik kapasitans 1.83 F/g, 1000. döngüdeki spesifik kapasitans 0.371 F/g olarak ölçülmüş, yüksek akım yoğunluğunda kapasitans tutma dayanımı düşmüş ancak 1000 döngü yapılan elektrota tekrar 2 A/g'da GCD testi uygulanmış, GCD eğrisinde bozulma gözlenmemiş, elektrottaki aktif malzemenin tükenmediği görülmüştür. Yapılan EIS analizi ise 17.51 Ω eşdeğer seri direnç, yüksek frekans bölgesinde 24 Ω yük transfer direnci ve düşük frekans bölgesinde kütle transfer direncinden kaynaklanan 174 Ω elektrot direnci ile gözenekli PP2C/CFE elektrotun pil tipi elektrot empedans davranışı gösterdiğini de desteklemiştir.

Table of contents of supporting information Experimental section S3 Combustion analysis data S8 Antibacterial assays S9 Antiviral assays S10 LogP calculations S10 Dynamic Light Scattering (DLS) experiments S11 DOSY NMR measurement S12 Computational Methods S12 STD and NOESY measurements S13 References S16 S3 Experimental section Azido-ristocetin aglycon (2b)

A facile synthesis of meso-unsubstituted but doubly fenced porphyrins is described. The required lryrroles are made by the Barton-Zard method from 2,4,6-triisopropylbenzaldehyde and 2,6-diphenylbenzaldehyde. An X-ray structure confirms the type l pattern. Synthetic porphyrin model compounds equipped with sterically shielding superstructures are the cornerstone of many important advances that successfully elucidated the hemoprotein chemistry in the last quarter of century.l,2 Metalloporphyrins derived from such protected structures could escape from falling into the thermodynamically sink-tt-peroxo or la-oxo bridging complex-when exposed to 02 or "oxene" species

To study dye-sensitized solar cells (DSSCs) with core-modified porphyrins as the sensitizing dyes, three porphyrins with an ethynyl benzoic acid as an anchoring group are prepared. The properties of free-base regular porphyrin (N4), thiaporphyrin (N3S) and oxaporphyrin (N3O) were thoroughly studied by spectroscopic methods, DFT calculations, and photovoltaic measurements. Replacing one of the porphyrinic core nitrogen atoms by oxygen or sulfur considerably changes the absorption spectra. The Soret band of the N3O and N3S observed bathochromic shifts of 3-9 nm while the Q band reaches 700 nm to the near-infrared region. The overall conversion efficiencies of the DSSCs based on these porphyrins are in the order N4 (3.66%) >> N3S (0.22%) > N3O (0.01%). The time-correlated single photon counting observed short fluorescence lifetimes for N3O adsorbed both on TiO 2 and Al 2 O 3 which explicates the poor efficiency of DSSC using N3O as the photosensitizer.

The chemistry of vanadyl porphyrins has been explored using vanadyl octaethylporphyrin as a substance in petroleum porphyrins, crude oils and bitumen. The structural, electronic, thermodynamic, spectroscopic properties are described. The geometry’s optimization of this molecule was done by Density Functional Theory (DFT) using the hybrid Beck three-parameter hybrid functional combined with Lee-Yang-Parr correlation functional (B3LYP) and 6-31G(d) standard basis set. All calculations have been made in the gas phase and in different solvents: benzene, benzonitrile, tetrachloromethane and chloroform. The calculated infrared spectrum was compared with experimental spectroscopic data, and the vibrational assignment was provided. An electron density analysis in terms of natural bond orbitals was conducted to determine the nature of the bonds between the vanadium and nitrogen atoms. The spatial representation of the associated molecular orbitals helped to explain the formation of the V-N b...

Bromination of (meso-tetraphenyltetrabenzoporphyrinato)palladium(II) with bromine in the presence of tetramethylammonium bromide occurs exclusively at the benzene rings fused to the porphyrin system while the phenyl rings in the meso positions are not involved. The corresponding octabromo-substituted complex was obtained using a large excess of bromine on prolonged reaction time. The complex was isolated and characterized by 1 H NMR spectra, electronic absorption spectra in the UV and visible regions, and MALDI-TOF mass spectra. It was assigned the structure of symmetric (

Two new conjugated pophyrin-based systems (dimers 3 and 4) endowed with suitable crown ethers have been synthesized as receptors for a fullerene-ammonium salt derivative (1). Association constants in solution have been determined by UV-vis titration experiments in DCM at room temperature. The designed hosts are able to associate up to two fullerene-based guest molecules and present association constants as high as 5 x 10(8) M(-1). Calculation of the allosteric cooperative factor  for supramolecular complexes [3·12] and [4·12] showed a negative cooperative effect in both cases. The interactions accounting for the formation of the associates are based, firstly, on the complementary ammonium-crown ether interaction and, secondly, on the π-π interactions between the porphyrin rings and the C60 moieties. Theoretical calculations have evidenced a significant decrease of the electron density in the porphyrin dimers 3 and 4 upon complexation of the first C60 molecule, in good agreement wi...

Water pollution due to global economic activity is one of the greatest environmental concerns, and many efforts are currently being made toward developing materials capable of selectively and efficiently removing pollutants and contaminants. A series of β-ketoenamine covalent organic frameworks (COFs) have been synthesized, by reacting 1,3,5-triformylphloroglucinol (TFP) with different C2-functionalized and nonfunctionalized diamines, in order to evaluate the influence of wall functionalization and pore size on the adsorption capacity toward dye and heavy metal pollutants. The obtained COFs were characterized by different techniques. The adsorption of methylene blue (MB), which was used as a model for the adsorption of pharmaceuticals and dyes, was initially evaluated. Adsorption studies showed that –NO2 and –SO3H functional groups were favorable for MB adsorption, with TpBd(SO3H)2-COF [100%], prepared between TFP and 4,4′-diamine- [1,1′-biphenyl]-2,2′-disulfonic acid, achieving the...

Covalent organic frameworks (CoFs) are a class of important porous materials that allow atomically precise integration of building blocks to achieve pre-designable pore size and geometry; however, pore surface engineering in CoFs remains challenging. Here we introduce pore surface engineering to CoF chemistry, which allows the controlled functionalization of CoF pore walls with organic groups. This functionalization is made possible by the use of azideappended building blocks for the synthesis of CoFs with walls to which a designable content of azide units is anchored. The azide units can then undergo a quantitative click reaction with alkynes to produce pore surfaces with desired groups and preferred densities. The diversity of click reactions performed shows that the protocol is compatible with the development of various specific surfaces in CoFs. Therefore, this methodology constitutes a step in the pore surface engineering of CoFs to realize pre-designed compositions, components and functions.

Syntheses of soluble tetrabenzoporphyrins (TBP) and tetranaphtho[2,3]porphyrins (TNP), with multiple substituents in the conjugated aromatic rings but bearing no substituents in the mesopositions, is reported. Both types of porphyrins were obtained by direct aromatization of precursor porphyrins, annealed with either cyclohexene or dihydronaphthalene fragments. TBPs and TNPs possess powerful absorption bands in the near-infrared (λ 610-710 nm, ϵ = 100,000-300,000 M-1 cm-1) and exhibit strong luminescence. Free bases and Zn complexes fluoresce with quantum yields of up to 50%, whereas Pd and Pt complexes phosphoresce in solutions at ambient temperatures. Remarkably, the phosphorescence quantum yields of Pd and Pt TBPs reach as high as 20-50%, which places them among the brightest near-infrared phosphors known to date.

ÐUse of pivalaldehyde in mixed acid-catalyzed condensations of an aryl aldehyde with pyrrole allows the isolation and structural characterization of stable porphomethenes (5,10,15,22-tetrahydroporphyrins) and porphodimethenes (both 5,10-and 5,15-diphydroporphyrins) as intermediates of porphyrin synthesis. Crystal structures reveal the importance of the absolute con®guration at the sp 3-hybridized centers for the oxidation and stability of these (bio)synthetic intermediates.

The synthesis of unprecedented energy transfer triads containing a near-infrared (NIR) emissive bacteriochlorin subunit and two diketopyrrolopyrrole (DPP) moieties linked to each other via ethynyl or zero-carbon spacers is presented. Their optical and fluorescence properties were determined in CHCl3 and toluene. These photophysical measurements highlight the ability of DPP scaffold to act as an effective energy donor, which once excited in the range 450-550 nm resulting nearly exclusively NIR emission of hydroporphyrin (ETE > 96%). Since DPP dyes are valuable structurally tunable fluorophores that may be used in the construction of high-performance multicomponent photoactive systems, their spectral compatibility with bacteriochlorin chromophore demonstrated through this work, is an important first step toward the rational design of novel and innovative hybrid NIR fluorophores inspired by (bacterio)chlorophylls and suitable for biomedical applications.

African surnames are full of praises that plays a key role in understanding the behaviour of the individual or clan as a whole.In this paper one will take a brief analysis of the Maseko surname praises. In the Maseko praise one will get to learn the history of their Maseko clan and their past and present behaviour.

Two types of SBA-15 mesoporous silica were functionalized with different nitrogen-carbon chain lengths (long and short-chain) and then used as solid supports for immobilization of manganese(III) complex of meso-tetrakis(4-carboxyphenyl)porphine, [SBA-15-short-chain-NH2@Mn(TCPP)OAc] and [SBA-15-long-chain-NH2@Mn(TCPP)OAc]. The prepared catalysts were characterized by powder X-ray diffraction (XRD), FT-IR and UV-Vis spectroscopy. The loading of catalyst onto porous materials was determined by atomic absorption spectroscopy. Thermal analysis also demonstrated that the immobilized catalysts are thermally stable up to almost 400 ˚C. A comparative study based on the difference in chain length of the functional groups of SBA-15 in the oxidation of olefins was carried out in the presence of urea hydrogen peroxide (UHP) as oxidant and acetic anhydride as an activator. The novel long-chain catalyst was designed to improve performance of the catalytic activity.

Two types of SBA-15 mesoporous silica were functionalized with different nitrogen-carbon chain lengths (long and short-chain) and then used as solid supports for immobilization of manganese(III) complex of meso-tetrakis(4-carboxyphenyl)porphine, [SBA-15-short-chain-NH2@Mn(TCPP)OAc] and [SBA-15-long-chain-NH2@Mn(TCPP)OAc]. The prepared catalysts were characterized by powder X-ray diffraction (XRD), FT-IR and UV-Vis spectroscopy. The loading of catalyst onto porous materials was determined by atomic absorption spectroscopy. Thermal analysis also demonstrated that the immobilized catalysts are thermally stable up to almost 400 ˚C. A comparative study based on the difference in chain length of the functional groups of SBA-15 in the oxidation of olefins was carried out in the presence of urea hydrogen peroxide (UHP) as oxidant and acetic anhydride as an activator. The novel long-chain catalyst was designed to improve performance of the catalytic activity.

As part of our continuing efforts to develop second generation photodynamic therapeutic agents [1], we synthesized three pentacyclic azine dyes that were designed with the aid of MNDO calculations to absorb visible light having wavelengths longer than 600 nm. Photophysical measurements for the azine dyes 1,4,8,11‐tetraethyl‐1,2,3,4,8,9,10,11,13‐nonahydrodipyrazino[2,3‐b:2′, 3′‐i] phenazinium acetate, 13, 1,4,8,11‐tetraethyl‐2,3,4,8,9,10,11,12,13‐octahydro‐13‐methyldipyrazino[2,3‐b:2,3′‐i]phenazinium iodide, 14, and l,4,8,11,13‐pentaethyl‐2,3,4,8,9,10,11,12,13‐octahydrodipyrazino[2,3‐b:2′,3′‐i]phenazinium iodide, 15, are highlighted by a 35 nm red shift in their absorption spectra and a 5–7 fold increase in their singlet oxygen quantum yield relative to tricyclic model compounds 3,7‐bis(diethylamino)phenazinium chloride, 20, and 3,7‐bis(diethylamino)‐5‐ethyl‐phenazinium iodide, 21, which were also synthesized for this study. Incorporation of rigid peripheral tetrahydropyrazino ring s...

Isopropanol, THF, sulfuric acid (95-97%), hydrochloric acid (37%) were purchased from Merck. All the chemicals were used directly without any pretreatment. Product analysis: HMF, FFCA, DFF and FDCA were analysed by HPLC (Agilent Technologies, 1200 series) and confirmed with isolation yield. HPLC working conditions: column (Agilent Hi-Plex H, 7.7 × 300 mm, 8 μm), solvent 10mM H 2 SO 4 , flow rate 0.7 ml/min, 25 o C, DAD detector (280 nm for HMF, DFF and FFCA; 254 nm for FDCA and HFCA). The retention time for detected compounds were 20.7

Condensation of phenyldipyrromethane with bisnaphthaldehyde 3 leads to unexpected formation of the scrambled 5,10-bridged porphyrin 5; this unprecedented selectivity suggests that an alternative scrambling mechanism to dipyrromethane acidolysis is operating.

The chemistry of vanadyl porphyrins has been explored using vanadyl octaethylporphyrin as a substance in petroleum porphyrins, crude oils and bitumen. The structural, electronic, thermodynamic, spectroscopic properties are described. The geometry’s optimization of this molecule was done by Density Functional Theory (DFT) using the hybrid Beck three-parameter hybrid functional combined with Lee-Yang-Parr correlation functional (B3LYP) and 6-31G(d) standard basis set. All calculations have been made in the gas phase and in different solvents: benzene, benzonitrile, tetrachloromethane and chloroform. The calculated infrared spectrum was compared with experimental spectroscopic data, and the vibrational assignment was provided. An electron density analysis in terms of natural bond orbitals was conducted to determine the nature of the bonds between the vanadium and nitrogen atoms. The spatial representation of the associated molecular orbitals helped to explain the formation of the V-N b...

On the basis of calculated data on the electron structures of condensed isoindoles with a nodel nitrogen atom it is hypothesized that these compounds may act as dienes in the Diels-Alder reaction. Conclusions regarding the relative activities and the peculiarities of cycloaddition in the investigated structures were drawn from the static reactivity indexes obtained within the Pariser-Parr-Pople approximation. Computational methods, together with kinetic studies, are currently the chief sources of information regarding the reactivities of dienes and dienophiles in the Diels-Alder reaction and its stereochemistry and mechanism. Data obtained in recent years [1-5] show that the Woodward-Hoffmann theory [6], which is acknowledged by organic chemists, is not absolute. More thorough and elegant experimental investigations have demonstrated the possibility of the realization of "forbidden" (from the point of view of the theory of orbital syrmnetry) processes [7], as well as a two-step mechanism of the Diels-Alder reaction, in contrast to the classical one-step synchronous process [I, 3, 59 8]. Chiefly butadiene, polyenes, benzene, polyacenes, and cyclopentadiene have been included among the dienes that have been investigated by quantum-chemical methods. However, calculations of heterocyclic dienes began to be realized only recently [9, i0]. In particular, several explanations were proposed in [Ii, 12].

meso‐Chlorinated bicyclo[2.2.2]octadiene‐fused porphyrins 2 (ClnTBCODPs; n = 1–4) have been synthesized by chlorination of the free base TBCODP‐H2 (1‐H2) using N‐chlorosuccinimide (NCS). The chlorinated derivatives were easily separated by column chromatography on silica gel to give 2‐H2 in good yields. This method for the chlorination of porphyrin using NCS is mild, safe, and economic compared with the established procedure for the meso‐chlorination of porphyrins. We also discovered the unexpected meso‐chlorination of the porphyrin with dichlorodicyanobenzoquinone (DDQ) by single‐electron transfer. ClnTBCODPs 2 were converted into tetrabenzoporphyrins (ClnTBPs) 3 in 100 % yields by retro‐Diels–Alder reaction. The derived compounds were characterized by NMR spectroscopy, UV/Vis spectrophotometry, cyclic voltammetry (CV), X‐ray crystallography, and organic field‐effect transistor (OFET) characteristics. The introduction of chlorine at the meso positions of the TBPs drastically change...

Phase-transfer catalysis (PTC) is a well-known useful tool to develop sustainable processes. Benefits deriving from using PTC are particularly evident in oxidation chemistry where it has been possible to replace many toxic, aggressive reagents with harmless and milder oxidants such as bleach or hydrogen peroxide. 49 the oxidant is undoubtedly the main factor that defines the 50 sustainability of an oxidation reaction. Although molecular 51 oxygen is an ideal oxidant, it also often exhibits poor selectivity 52 due to competitive combustion. Moreover, conversions should 53 be kept low to control overoxidation and heat generation. 54 On the other hand, sodium hypochlorite and hydrogen 55 peroxide have emerged as useful reagents to perform oxidations 56 under mild reaction conditions and without metallic waste. 57 Bleach is particularly inexpensive as witnessed by its use to 58 inhibit microbial growth in swimming pools, whereas H 2 O 2 has 59 recently been used in the manufacture of bulk chemicals such as 60 propylene oxide. 6 Indeed, the progress of process technology 61 and the increasing economies of scale allowed the manufactur-62 ing cost of H 2 O 2 to decrease. Moreover, new promising 63 methods will probably make this reagent still cheaper. 7 64 2.1. Hydrogen Peroxide. Excluding oxygen, H 2 O 2 is the 65 most valuable oxidant with an atom efficiency of 47%, 66 generating water as the only byproduct. Lipophilic quaternary 67 ammonium salts such as Aliquat 336 or Hex 4 N + Br − are capable 68 to efficiently extract H 2 O 2 from the aqueous to the organic 69 phase, allowing fast oxidation reactions under PTC conditions. 70 In some cases the H 2 O 2 oxidation processes are accelerated by 71 the addition of molybdates or wolframates as cocatalysts. 8 72 For example, a halide and organic solvent free oxidation of 73 primary and secondary alcohols with H 2 O 2 under liquid−liquid 74 (LL) PTC conditions afforded the corresponding carboxylic 75 acids and ketones with high yields in short reaction times. 9 76 The direct oxidation of cyclohexene 1 to adipic acid 2 is one 77 of the most remarkable oxidation reactions under PTC 78 s1 conditions (Scheme 1). 10 79 In fact, adipic acid is manufactured as much as 3.5 million 80 tons, mainly for nylon-6.6 production. However, the classical 81 commercial process relies on a hazardous cyclohexane air 82 oxidation providing a mixture of cyclohexanol and cyclo

Using as example 3-methoxy-1-(2-methoxyethyl)-2-methylsulfanylpyrrole, obtained in one preparative stage from α-lithiated methoxyallene and 2-methoxyethyl isothiocyanate, a facile cleavage of a CO bond in the N-(2-methoxyethyl) substituent by the t-BuOK-DMSO system has been discovered, opening access to a new class of N-vinylpyrroles (through β-elimination of methanol).

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A novel heterogeneous catalyst was developed by immobilization of the robust Mn(TDCPP)Cl on an inorganic support by a strong covalent bond through the ␤-position of the macrocycle. This new material has demonstrated to be an active, selective and reusable catalyst in clean epoxidation reactions using hydrogen peroxide as oxidant.

A biomimetic and environmentally benign approach, with potential application in the oxidative desulfurization procedure for several organosulfur compounds (thioanisol, diphenylsulfide, benzothiophene, 2-methylbenzothiophene, 3-methylbenzothiophene, benzothiophene-2-methanol and dibenzothiophene), is presented. The current methodology involves manganese porphyrins as catalysts, which are well-known biomimetic models of cytochrome P450 enzymes, and hydrogen peroxide as the oxygen source. [Mn(TDCPP)Cl] and [Mn(TPFPP)Cl], the manganese porphyrin complexes used in this study, proved to be very efficient catalysts, affording high conversions of all the substrates tested into the corresponding sulfones. The conversion of benzothiophene reaches 99.9% in 90 min, whereas the conversion of dibenzothiophene attains 99.9% after 120 min of reaction, both for a catalyst/substrate molar ratio of 150. The substituted benzothiophenes give rise to similar results, being the best conversions obtained for a catalyst/substrate molar ratio of 150. The oxidation of a model fuel (solution of benzothiophene, 3-methylbenzothiophene, 2-methylbenzothiophene, and dibenzothiophene in hexane) was performed using hydrogen peroxide and [Mn(TDCPP)Cl] as catalyst, achieving total conversion into the corresponding sulfones.

Phenyl-substituted tetra-, penta-, hexa- and octacenes were easily obtained starting from a readily available naphthalene-based bisaryne precursor. This approach to large acenes involves a sequence of two Diels-Alder cycloadditions with dienones followed by two CO extrusion reactions.

The selective oxidation of 5-hydroxymethyl furfural (HMF) to 2,5-diformylfuran (DFF) is one of the rapidly growing research area due to having its own importance in the fuel technology. We report a new heterogeneous catalyst for the oxidation of HMF to DFF in aqeous medium using a carbon soot deposited on magnetite (Fe3O4@C). Further, the potentiality of our catalyst has also been realized in direct production of DFF from biomass (using either fructose or glucose) with high conversions via two consecutive steps.

Iodophenyl)-10,15,20-tris(3",5"-di-tert-butylphenyl)zincporphyrin (1) 3,5-di-tert-butylbenzaldehyde (6.66 g, 30.58 mmol), 3-iodobenzaldehyde (1.42 g, 6.12 mmol) and pyrrole (1.70 mL, 24.40 mmol) in propionic acid (100 mL) were heated to reflux for 6 h. The reaction mixture was cooled down to room temperature and the solvent was removed under reduced pressure. The solid was redissolved in CH 2 Cl 2 (300 mL) and Et 3 N (15 mL) was added. The organic layer was washed with H 2 O (4 × 300 mL), dried over Na 2 SO 4 and the solvent was removed under reduced pressure to leave a black solid. The crude mixture was treated with excess Zn(OAc) 2 •2H 2 O (15 g) in CHCl 3 /MeOH mixture (10% MeOH) and gently heated for 10 mins. The solution was washed with H 2 O, dried over Na 2 SO 4 and the solvent was removed under reduced pressure. The reaction mixture was purified by column chromatography on silica gel eluted with CH 2 Cl 2 /hexane (1/3) and the second fraction was collected. The fraction was purified again by column chromatography under the same conditions to yield 1 as purple solid (1.08 g, 16%). Recrystallisation from CH 2 Cl 2 solution layered with MeOH afforded 1 of higher purity.

The syntheses of new aromatic 30π heptaphyrins either through a [5 + 2] or a [4 + 3] acid-catalyzed condensation and oxidative coupling reactions of easily available and air-stable precursors are reported. The methodology followed is not only simple and efficient but also allows synthesis of a range of heptaphyrins with different heteroatoms in the core. The oxidative coupling reactions of modified tripyrranes 11 and tetrapyrranes 12 were found to be dependent on the acid concentration used and as well as the substituents present on the meso position. The change of meso aryl substituents in 11 and 12 to meso mesityl substituents gave a new heptaphyrin 18. The structural characterization has been done with extensive 1 H and 2D NMR studies. The heptaphyrins reported here show rich structural diversity when the connections of the heterocyclic rings are altered, and accordingly, one ring and two ring inversions have been observed. By a judicious choice of the precursors it has been possible to control the site of ring inversion either in the bithiophene unit or in the tripyrrane unit. Theoretical calculations performed on three different heptaphyrins, 4, 5, and 17, also reveal that the inverted structures are ∼35-40 kJ lower in energy relative to the corresponding noninverted structures. Furthermore, one of the heptaphyrins 10c shows the presence of two conformers in solution in the ratio 1:2 and no interconversion between the conformers have been observed in the temperature range of 343-228 K. On protonation, the aromaticity and the ring inversions are retained and the ∆δ values vary in the range 10.07-20.59 ppm. The energies of the Soret maxima and the HOMO-LUMO gap vary linearly with the increase in π electrons further justifying the aromatic nature of the heptaphyrins.

Demand for new colorimetric sensors for toxic anions has widely increased in the last ten years, because it is an inexpensive technique, in which the analyte is naked-eye detectable. Regarding this issue, two new corrole derivatives 2 and 3 were successfully synthetized and characterized by elemental analysis, 1 H and 19F-NMR, MALDI-TOF-MS, UV-Vis absorption and emission spectra. b-Vinyl-corrole 1 was prepared by the Wittig reaction of b-formyl-corrole with phosphorus ylide. Subsequent treatment of b-vinyl-corrole with dimethyl acetylenedicarboxylate afforded compounds 2 and 3. The sensorial ability of the two new corrole derivatives towards fluoride, cyanide, acetate and phosphate anions was carried out by absorption and emission spectroscopy. Compound 2 shows to be colorimetric to cyanide, whereas a change of colour from green to colourless was visualized. In addition the highest association constants were obtained for compounds 2 and 3 in the presence of cyanide that are able to quantify a minor amount of cyanide (ca. 1.00 lM).

Knoevenagel condensation has been utilized as an alternative way to synthesize a series of β-vinylsubstituted porphyrins and porphyrin dyads with good to excellent yields. The condensation of β-formyl porphyrins and phenylacetonitriles allows control of the substitution pattern and metal centres in the porphyrin dyads, allowing the use of metallated synthons. While the optical and electronic properties of the resulting porphyrin dyes are perturbed by the presence of the cyano substituent, this does not significantly affect their use. For example, Raman spectroscopy, in agreement with density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations, show porphyrin electronic transitions with delocalization of frontier molecular orbital electron density onto the β substituent. A comparison of the photovoltaic performance of a carboxylated cyanostyryl condensation product and the unsubstituted analogue in dye-sensitized solar cells (DSSCs) was made. Although the devices showed similar efficiency, the device containing the cyano-substituted dye showed an extended incident photon-to-current conversion efficiency (IPCE) due to a slight red-shift in absorption and an increase in photovoltage as a result of a longer electron lifetime. This minimal change in light-harvesting performance highlights the potential of this Knoevenagel synthetic methodology for producing light-harvesting porphyrin dyes.

In this study, the electrochemical behavior of free base and zinc meso-substituted porphyrins is examined by cyclic voltammetry (CV) and density functional theory (DFT). The results show that the half-wave oxidation potential splitting of the two oxidation states (∆E= 2(nd) E1/2 - 1(st) E1/2) of tetraphenylporphyrin (H2TPP) and its zinc complex (ZnTPP) are higher than those of porphyrins and their zinc complexes with meso-substituted five-membered heterocylic rings. The ∆E values follow the trend of TPP > T(3'-thienyl)P > T(3'-furyl)P > T(2'-thienyl)P for both meso-porphyrins and their respective zinc complexes. By employing DFT calculations, we have found that the trend of ∆E values is consistent with that of highest spin density (HSD) distribution and HOMO-LUMO energy gaps of cationic radicals as well as the π-conjugation between central porphyrin and meso-substituted rings. Also, they exhibit the better resonance between the porphyrin ring with meso-substitut...

Recently we described a new synthesis of C,D-ring symmetric chlorins 11, involving 2+2 condensation of bis-formyl-dihydrodipyrrins 9 with symmetrically substituted dipyrromethane diacids 10 (Method I). However, while versatile in many aspects, Method I was unsuited to the broader goal of synthesizing fully non-symmetric chlorins of general structure 15, which requires regioselective control over the reacting centers in the A,B-and C,D-ring components. In this paper we describe four new 2+2 strategies that accomplish this differentiation (Methods II-V). Of these, Method V, which combines operational simplicity with moderate to high product yields, proved to be the most effective route, exploiting reactivity differences between the two formyl groups of A,Brings 9 to impart excellent regioselectivity. Methods II-IV are also useful alternatives to Method V, although in some cases the appropriately functionalized precursors are less readily available. All four approaches generate single regioisomers of diversely substituted chlorins, and in every case the 2+2 condensation is accomplished in a simple, one-flask procedure without need for additives such as oxidizing agents or metals. Taken together, these methodologies provide expanded access to an array of chlorins for SAR studies that may advance the effectiveness of PDT and other applications.

C,D-Ring symmetric chlorins 8 were prepared in 47-85% yield, on scales up to several hundred milligrams, by condensation of appropriately substituted bis-formyldihydro-dipyrrins 6 and dihydropyrromethane bis-carboxylic acids 7 in 5% TFA/CH 2 Cl 2 (25 examples). Target chlorins were chosen to systematically probe the effect of lipophilic and hydrophilic substituents on tissue partitioning and cellular membrane penetration in photodynamic therapy (PDT).

Phase-transfer catalysis (PTC) is a well-known useful tool to develop sustainable processes. Benefits deriving from using PTC are particularly evident in oxidation chemistry where it has been possible to replace many toxic, aggressive reagents with harmless and milder oxidants such as bleach or hydrogen peroxide. 49 the oxidant is undoubtedly the main factor that defines the 50 sustainability of an oxidation reaction. Although molecular 51 oxygen is an ideal oxidant, it also often exhibits poor selectivity 52 due to competitive combustion. Moreover, conversions should 53 be kept low to control overoxidation and heat generation. 54 On the other hand, sodium hypochlorite and hydrogen 55 peroxide have emerged as useful reagents to perform oxidations 56 under mild reaction conditions and without metallic waste. 57 Bleach is particularly inexpensive as witnessed by its use to 58 inhibit microbial growth in swimming pools, whereas H 2 O 2 has 59 recently been used in the manufacture of bulk chemicals such as 60 propylene oxide. 6 Indeed, the progress of process technology 61 and the increasing economies of scale allowed the manufactur-62 ing cost of H 2 O 2 to decrease. Moreover, new promising 63 methods will probably make this reagent still cheaper. 7 64 2.1. Hydrogen Peroxide. Excluding oxygen, H 2 O 2 is the 65 most valuable oxidant with an atom efficiency of 47%, 66 generating water as the only byproduct. Lipophilic quaternary 67 ammonium salts such as Aliquat 336 or Hex 4 N + Br − are capable 68 to efficiently extract H 2 O 2 from the aqueous to the organic 69 phase, allowing fast oxidation reactions under PTC conditions. 70 In some cases the H 2 O 2 oxidation processes are accelerated by 71 the addition of molybdates or wolframates as cocatalysts. 8 72 For example, a halide and organic solvent free oxidation of 73 primary and secondary alcohols with H 2 O 2 under liquid−liquid 74 (LL) PTC conditions afforded the corresponding carboxylic 75 acids and ketones with high yields in short reaction times. 9 76 The direct oxidation of cyclohexene 1 to adipic acid 2 is one 77 of the most remarkable oxidation reactions under PTC 78 s1 conditions (Scheme 1). 10 79 In fact, adipic acid is manufactured as much as 3.5 million 80 tons, mainly for nylon-6.6 production. However, the classical 81 commercial process relies on a hazardous cyclohexane air 82 oxidation providing a mixture of cyclohexanol and cyclo