Intramolecular hydrogen bonds (IHBs) play a central role in the molecular structure, chemical reactivity and interactions of biologically active molecules. Here, we study the IHBs of seven related o-carbonyl hydroquinones and one structurally-related aromatic lactone, some of which have shown anticancer and antioxidant activity. Experimental NMR data were correlated with theoretical calculation...

The synthesis and properties of a novel class of ortho-dialkylamino-substituted semisquaraines are described. The exceptionally low reactivity of the investigated compounds is caused by an intramolecular hydrogen bond as evidenced by experimental and computational studies. Although this constitutes the reason for our failed attempts to prepare poly(m-phenylene-alt-squaraine)s, the discovered in...

The title Schiff base compound, C25H19NO2S, crystallizes in a statistically disordered structure comprising keto and enol tautomeric forms. In the enol form, the benzenoid arrangment is promoted by a strong intra-molecular O-H⋯N hydrogen bond and adopts an E conformation about the imine bond. In the keto form there is an intramolecular N-H⋯O hydrogen bond. In the crystal, an extended network of...

In the hydrazone molecule of the title compound, C(13)H(9)I(2)N(3)O(2)·CH(3)CN, the aromatic rings form a dihedral angle of 9.4 (3)°. In the crystal structure, inter-molecular I⋯N inter-actions [3.099 (4) Å] link hydrogen-bonded aggregates of the hydrozone and solvent molecules related by translation along the b axis into chains. An intramolecular O-H⋯N hydrogen bond forms an S(6) ring.

The title compound, C(11)H(14)N(2)O(2)S, was synthesized from furoyl isothio-cyanate and piperidine in dry acetone. The thio-urea group is in the thio-amide form. The thio-urea group makes a dihedral angle of 53.9 (1)° with the furan carbonyl group. In the crystal structure, mol-ecules are linked by inter-molecular N-H⋯O hydrogen bonds, forming one-dimensional chains along the c axis. An intram...

High-resolution spectra of the intramolecular bending modes of deuterated water dimer, (D2O)2, have been measured using a quantum cascade laser based cavity ringdown spectrometer. Two perpendicular bands have been observed and are assigned as the K(a) = 1 ← 0 and K(a) = 2 ← 1 bands of the bending mode of the hydrogen bond donor. The tunneling splittings in the complex are well-resolved, and it ...

The title Schiff base compound, C(13)H(9)BrClN(3)O(2)·CH(4)O, was derived from the condensation reaction of 3-bromo-5-chloro-salicylaldehyde with isonicotinohydrazide. The dihedral angle between the benzene and pyridine rings is 5.9 (2)°. In the crystal structure, mol-ecules are linked through N-H⋯O, O-H⋯O, and O-H⋯Br inter-molecular hydrogen bonds, forming dimers and chains. There is also an i...

In the title compound, C(19)H(19)NO(5), the furan-one unit makes a dihedral angle of 30.93 (6)° with the benzene ring and a dihedral angle of 9.51 (6)° with the aniline ring. In the crystal, inter-molecular C-H⋯O hydrogen bonds and C-H⋯π contacts link the mol-ecules into sheets. A weak intramolecular hydrogen bond is also observed.

The title compound, C(20)H(18)Cl(2)F(2)N(2)O(5), is considered to belong to the fourth generation of insecticides with properties such as high selectivity, low acute toxicity for mammals and high biological activity. An intramolecular N-H⋯O hydrogen bond results in the formation of a six-membered ring. In the crystal structure, intermolecular N-H⋯O and C-H⋯F hydrogen bonds link the molecules.