A new photoactive monoclinic polymorph (gamma-form) of 6-(2',4'-dinitrobenzyl)-2,2'-bipyridine was obtained from an acetone-methanol solution. The crystal structure was compared with those of two polymorphs reported previously (photoactive orthorhombic alpha-form and photoinactive monoclinic beta-form) and with structures of related nitrobenzylpyridines to explain the relation between the struc...

Dynamics of photochromism have been studied in anil compounds using femtosecond transient absorption and picosecond fluorescence spectroscopies. The experimental observations were compared with the theoretical results obtained Ž . from AM1–SCF calculations. Excited-state intramolecular proton transfer ESIPT and photochromic reaction were found to occur from the S state, whereas normal fluoresce...

Nanoporous frameworks are polymeric materials built from rigid molecules, which give rise to their nanoporous structures with applications in gas sorption and storage, catalysis and others. Conceptually new applications could emerge, should these beneficial properties be manipulated by external stimuli in a reversible manner. One approach to render nanoporous frameworks responsive to external s...

Three new isomeric asymmetric diarylethenes with a naphthyl moiety and a formyl group at the para, meta or ortho position of the terminal benzene ring were synthesized. Their photochromism, fluorescent-switch, and electrochemical properties were investigated. Among these diarylethenes, the one with a formyl group at the ortho position of benzene displayed the largest molar absorption coefficien...

Three (bola)amphiphilic spirooxazines have been synthesized and their photochromism has been characterized. The large biphotochromic structure of 2 significantly affects its conformational flexibility and the rate constants for thermal ring closure are particularly dependent on the lipid phase state. Two comprehensive ion permeation studies were performed to examine the effect of spirooxazine i...

The process of reversible coloration changes induced at least in one-direction by photoirradiation is referred to as photochromism.1) The two isomers of photochromic compounds differ in their geometrical and electrical structures. These geometrical and electrical differences lead to changes in the physical properties of the molecules, such as their absorption and fluorescence spectra, refractiv...