In the title compound, C(17)H(10)Br(2)O(5), the chromene ring is almost planar with minimal puckering [total puckering amplitude = 0.067 (4) Å]. The dihedral angle between chromeme ring system and phenyl ring is 3.7 (2)°. The crystal structure is stabilized by intermolecular C-H⋯O inter-actions and an intramolecular O-H⋯O hydrogen bond also occurs.

the interaction of dppa which is an important component in cellular membrane with molecules of water asmedia, cause some changes in geometry of dppa .in this study we focused our attention on comparing thismolecule with related hydrated complexes employing different basis sets at hartree-fock levels of theory. thetheoretical nmr shielding tensor of some imported atoms were also reported.

In the title salt, C(10)H(11)N(3) (2+)·2C(8)H(5)O(4) (-), doubly protonated 4,4'-dipyridylamine (dpa) cations participate in N-H⋯O hydrogen bonding with two hydrogen phthalate anions to form a neutral unit. Both anions contain an intramolecular O-H⋯O hydrogen bond. In the crystal structure, these units form two-dimensional layers through π-π stacking inter-actions with a centroid-to-centroid di...

In the title Schiff base, C(21)H(25)F(2)NO, the dihedral angle between the aromatic rings is 27.90(5)° and an intramolecular O-H⋯N hydrogen bond occurs. In the crystal, the molecules are linked by C-H⋯O, C-H⋯N and C-H⋯F interactions.

Anion photoelectron spectroscopy (PES) and electron energy-loss spectroscopy (EELS) probe different regions of the anionic potential energy surface. These complementary techniques provided information about anionic states of acetoacetic acid (AA). Electronic structure calculations facilitated the identification of the most stable tautomers and conformers for both neutral and anionic AA and dete...

The 1H and 15N NMR spectra of several 15N-labeled pyridoxal-5'-phosphate model systems have been measured at low temperature in various aprotic and protic solvents of different polarity, i.e., dichloromethane-d2, acetonitrile-d3, tetrahydrofuran-d8, freon mixture CDF3/CDClF2, and methanol. In particular, the 15N-labeled 5'-triisopropyl-silyl ether of N-(pyridoxylidene)-tolylamine (1a), N-(pyrid...

In the title compound, C(14)H(20)N(2)S(2), the 1,3,5-thia-diazinane-2-thione ring adopts an envelope conformation. The S=C bond length is 1.6776 (15) Å, whereas the S-C bond lengths are 1.7470 (15) and 1.8479 (17) Å. The intramolecular C-H⋯S hydrogen bond between the thione and the benzyl units along with the C-H⋯π interaction between the butyl group and the centroid of the benzene ring may be ...

The theoretical analysis of the energy of the conformers of 2@-deoxyribonucleosides presents some subtle but signiÐcant di†erences depending on the nature of the base linked to the sugar. In particular, 2@-deoxycytidine behaves uniquely. Among the structural parameters invoked to explain this phenomenon, one of the most intriguing is the CÈHÉ É ÉO intramolecular hydrogen bond in which the donor...

The 1:1 and 2:1 cocrystals of benzene-1,2,4,5-tetracarboxylic acid (BTA) and 4,40-bipyridine (BPY) have been studied using neutron diffraction at 215 and 20 K, respectively. BTA and BPY crystallize in a 1:1 ratio with 1.8 molecules of water, viz. 4,40-bipyridinium 2,5-dicarboxybenzene-1,4-dicarboxylate 1.8hydrate, C10H12N2 2+ C10H4O8 1.8H2O, (I), in the space group P1, with both BTA and BPY lyi...

The investigation of excited-state intramolecular proton transfer (ESIPT) has been carried out via the density functional theory (DFT) and the time-dependent density functional theory (TDDFT) method for natural product quercetin in dichloromethane (DCM) solvent. For distinguishing different types of intramolecular interaction, the reduced density gradient (RDG) function also has been used. In t...