Biokristallografie

A novel layered manganese(II) phosphate, Mn 3 (PO 4 ) 4 ‚2(H 3 NCH 2 CH 2 ) 3 N‚6(H 2 O), has been synthesized solvothermally using tris(2-aminoethyl)amine (TREN) as a template. The structure was solved ab initio using X-ray powder diffraction data and confirmed by molecular modeling. The compound was further characterized by SEM, IR spectroscopy, photoluminescence, and elemental and thermal analysis. The compound crystallizes in the trigonal space group P3 hc1 with a ) 8.8706(4) Å, c ) 26.158(2) Å, and V ) 1782.6(2) Å 3 . The structure consists of layers of corner sharing Mn(II)O 4 and PO 4 tetrahedra forming infinite [Mn 3 (PO 4 ) 4 ] 6macroanions with 4.6 net topology, sandwiched by layers of TREN and water molecules. The protonated TREN molecules provide charge balancing for the inorganic sheets; the interlayer stability is accomplished mainly by a network of hydrogen bonds between water molecules and the inorganic macroanions. This hybrid organic/inorganic layered material can be reversibly dehydrated.

Two dihydropyridines endowed with fluorine atoms (3) and fluorine and chlorine atoms (4) have been synthesized and structurally characterized by experimental X-ray analyses and theoretical calculations at the semiempirical (AM1) and ab initio (HF/6-31G*) levels. The results show that these compounds meet the required criteria to act as potential calcium channel modulators.

AbstractÐThe X-ray crystal structure of three substituted tetrahydrobenzo-4H-pyrans (6a±c) is presented and the experimental ®ndings compared with the theoretical values calculated at the semiempirical (AM1, PM3) and ab initio (HF/6-31G p ) levels. A good agreement between both experimental and theoretical data is found showing a¯attened boat conformation for the 4H-pyran ring and a pseudo-axial orientation of the aryl ring on the C4 position. The geometrical features of these systems (6a±c) reveal that they present the structural requirements to act as calcium antagonists. q

AbstractÐX-Ray analysis and semiempirical AM1 and ab initio HF/3-21G p and HF/6-31G p calculations reveal a favourable envelop conformation (A) for 3,5-disubstituted tetrahydro-2H-1,3,5-thiadiazines in which the N5 atom lies out of the main plane. NOE experiments show that this conformer (A) is also found in solution. q . Tetrahydro-2H-1,3,5-thiadiazine-2-thiones (TTT) (1) and the TTT derivative (2) studied in this work.