An o-hydroxyphenyl-containing spiropyran thermochromic colorant was designed and synthesized. The prepared compound is sensitive to temperature and has a reversible color change with temperature variation. X-ray diffraction analysis and variable-temperature NMR studies suggest that the thermochromism of the compound presumably involved a ring-opening C-O bond cleavage of the spiropyran moiety f...

In the mol-ecule of the title compound, C(11)H(14)N(2)O(4), a bifurcated intra/intermolecular N-H⋯(O,O) hydrogen bond occurs.The intramolecular component results in a non-planar six-membered ring with a flattened-boat conformation. In the crystal structure, the inter-molecular interaction links the mol-ecules into chains parallel to the b axis.

In the title compound, C(12)H(7)Cl(2)FN(2)O, the dihedral angle between the phenyl and pyridine rings is 42.5 (2) Å and an intramolecular N-H⋯N hydrogen bond occurs. The crystal structure is stabilized by C-H⋯O, C-H⋯F and C-Cl short contacts.

The title compound, C(16)H(17)NO, is a Schiff base which adopts the phenol-imine tautomeric form in the solid state. The mol-ecule is almost planar, with a dihedral angle of 4.61 (4)° between the aromatic rings. The molecular structure is stabilized by an intramolecular O-H⋯N hydrogen bond which generates a six membered ring.

An activated Michael acceptor type of probe by an intramolecular hydrogen bond has shown a selective fluorescence turn-on response to cyanide through a conjugated addition of the nucleophilic anion to the enone probe with a 1300-fold increase in its fluorescence intensity.

Two GFP analogues o-HBDI and o-HBMO have been designed and synthesized. The former shows no fluorescence while the latter shows strong fluorescence due to the formation of an intramolecular hydrogen-bond. At low temperatures, both molecules have strong fluorescence.

While purifying new polysubstituted 5-nitrosopyrimidines, the unique separation of pairs of rotamers as chemical species, stabilized by a single intramolecular hydrogen bond and differing only in nitroso group orientation, was achieved. This interesting stereochemical phenomenon is compared to the well-known atropisomerism.

In the title compound, C(21)H(18)O(6), a previously unknown coumarin derivative, the benzoyl substitutent makes a dihedral angle of 53.80 (16)° with the plane of the coumarin rings. An intramolecular O-H⋯O hydrogen bond is observed.

The mol-ecule of the title compound, C(14)H(10)BrClN(2)O(3), is planar [dihedral angle between the aromatic rings = 3.0 (2)°] and shows a trans configuration with respect to the C=N double bond. The crystal structure is stabilized by inter-molecular N-H⋯O hydrogen bonds and an intramolecular O-H⋯N interaction also occurs.

The possibility of tunable regioselective activation of a dinitrile towards nucleophilic attack was demonstrated. For that, a sulfo-arylhydrazone unit was introduced into malononitrile and the thus formed intramolecular hydrogen bond systems assisted specific nucleophilic attacks to the cyano moieties leading to a variety of amidines, carboxamides and iminoesters depending on the nucleophiles a...