Core-modified expanded porphyrins with large third-order nonlinear optical response

The third-order nonlinear optical response through measurement of two-photon absorption cross-sections (TPACS) for aromatic core-modified expanded porphyrin analogues by a femtosecond open aperture Z-scan method is reported. The values reported here are among the largest known so far in the literature for any organic molecules.     

Designing specific inhibitors against dihydrofolate reductase of W. bancrofti towards drug discovery for lymphatic filariasis

Structural Chemistry - Lymphatic filariasis (LF) is one among the leading neglected diseases caused by mosquitoe-borne parasite Wuchereria bancrofti to humans. Though drugs are available for the...     

Crystal structures of N1, N5‐dibenzoyltetrahydro‐4‐methyl‐1, 5‐benzodiazepin‐2‐one (DBTBO) and tetrahydro‐4‐methyl‐1, 5‐benzodiazepin‐2‐one (TBO)

Adducing structural analogies between the two fused systems, N1, N5‐Dibenzoyltetrahydro‐4‐methyl‐1,5‐benzodiazepin‐2‐one, C₂₄H₂₀N₂O₃ (DBTBO CCDC 200341) and Tetrahydro‐4‐methyl‐1,5‐benzodiazepin‐2‐one, C₁₀H₁₂ N₂O (TBO CCDC 200342) helps to find the pharmacological differences from the view point of variant hetero atom substitutions in the hetero cycle. Both the diazepines crystallized in identical monoclinic space group P2₁/n with a = 14.1134(1) Å, b = 9.2444(1) Å, c = 16.3812(1) Å; β = 107.11(1)º, V = 2042.7(3) ų for DBTBO and a = 9.3363(7) Å, b = 10.4895(8) Å, c = 9.9852(7) Å, β = 91.314(1)º, V = 977.62(1) ų for TBO, respectively. The two structures were solved by direct methods and refined by full‐matrix least‐squares procedure to final R‐values of R1 = 0.0575(DBTBO) and R1 = 0.0984(TBO). Structural differences include non‐identical boat conformations of these seven‐membered rings and the different non‐bonding interactions in the benzodiazepine pair.     

The Crystal and Molecular Structure of 9-(3-Pentyl)-3,4,6,7,9,10-hexahydro-1,8(2H,5H) -acridine-dione

The crystal structure of the title compound is described. The structure has two molecules in the asymmetric unit and it crystallizes in the orthorhombic space group Pca21 with Z = 8. The unit cell dimensions are a = 14.574(2), b = 8.924(1) and c = 24.704(10) Å, V = 3212.7(14) ų, D_calc = 1.188 gcm^-3. All the rings of the molecule A adopt sofa conformation. One of the outer rings of molecule B adopts distorted sofa while the other two rings adopt sofa conformation.     

The Curious Case of a Parasitic Twin of the Corroles

An expanded porphyrinoid has been obtained by a simple ring expansion from a contracted porphyrinoid, namely corrole. Spectroscopic, structural, and computational investigations reveal peculiar π‐conjugation and geometry. The effect of extended π‐conjugation is evident from perturbed redox behavior and photophysical properties. Owing to the strong diatropic ring current of the corrole and cross‐conjugation, the molecule exhibits a non‐aromatic nature for the expanded π‐circuit, as evident from NMR studies.     

Near Supramolecular Isomorphism Involving Homologous Solvents: Pyrimethaminium Terephthalate Methanol Solvate and Pyrimethaminium Terephthalate Ethanol Solvate

Abstract  

Two nearly isostructural pseudopolymorphic forms of pyrimethaminium terephthalate have been synthesized and their supramolecular architectures analyzed. In both the crystals, the protonated pyrimethamine (PMN) cation interacts with the carboxylate anion via N–H···O hydrogen bonds to form the robust R₂²(8) motif. The centrosymmetrically (N–H···N) paired PMN cations are bridged on either sides by interaction of the solvent molecules with the amino groups (N–H···O) of PMN cations. The combination of two R₂²(8) motifs formed between the PMN cations and PMN cation solvent, leads to the formation of the complementary DADA (D = hydrogen bonded donor, A = hydrogen bonded acceptor) array of quadruple hydrogen bonds. The solvent molecule further interacts with the corresponding anion via O–H···O hydrogen bonds. Moreover, both the solvates exhibit several edge to face stacking interactions. They have in common, two C–H···π interactions; one between the symmetry related cations and other between the cation and anion. The molecular packing of the ethanol solvate is further strengthened by C–H···O and C–H···π interaction between the solvent and the ions.     

Structural characterization of 2,6-di(2-thioenyl)-3,5-dimethyl piperidin-4-one (DTMP) in solution and solid state

The structure of the title compound, DTMP (C₁₅H₁₇NS₂O), has been investigated in solution and in the solid state by IR, NMR and X-ray methods. The crystal structure was solved by direct methods and refined by least-squares procedures to anR-factor of 0.073. The piperidine ring adopts achair conformation. The methyl and thioenyl rings are in theequatorial position. The angle between the best plane of the piperidine ring and the thioenyl rings A and B are 88.1(1)° and 89.5(1)°, respectively.DCB contribution No. 846