Acylated 2-(N-arylaminomethylene)benzo[b]thiophene-3(2H)-Ones: Molecular Switches with Varying Migrants and Substituents

Synthesis and properties of photochromic acylated 2-(N-arylaminomethylene)benzo[b]thiophene-3(2H)-ones are described. Their structure largely depends on the nature of acyl migrant and in a less degree on N-aryl substituent

Synthesis of Novel Iono- and Photochromic Spiropyrans Derived from 6,7-Dihydroxy-8-Formyl-4-Methyl-2H-Chromene-2-One

Novel photochromic spiropyrans (SPPs) containing 6′-hydroxy group were synthesized and their spectral properties as well as abilities for complexation with metal ions studied. In solutions they exist as equilibrium mixture of spirocyclic (A) and merocyanine (B) isomers. The largest content of merocyanine form was found for the derivative with an electron-donating methyl group in position 5 of hetaryl fragment. The irradiation of SPPs in acetonitrile shifts the equilibrium to the B form. Similar effect causes the addition of metal cations due to formation of colored complexes with merocyanine isomers

Synthesis and Photo- and Ionochromic and Spectral-Luminescent Properties of 5-Phenylpyrazolidin-3-one Azomethine Imines

Photochromic 5-phenylpyrazolidin-3-one-based azomethine imines containing 2-((1H-imidazol-2-yl)methylene) 1, 2-(pyridin-2-ylmethylene) 2, 2-(quinolin-2-ylmethylene) 3, and 2-((8-hydroxyquinolin-2-yl)methylene) 4 substituents were synthesized. All the compounds exist in the ring-opened O forms. Under irradiation with light of 365 nm, compounds 1–4 undergo thermally reversible isomerization into ring-closed bicyclic diaziridine isomers C. Azomethine imines 1–3 exhibit properties of ion-active molecular “off-on” switches of fluorescence when interacting with F− or AcO− anions. Compound 4 represents a bifunctional chemosensor demonstrating a colorimetric “naked-eye” effect for Ni2+ cation and complete fluorescence quenching in the presence of H+, F−, and CN− ions

Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline group

A series of novel photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline receptor substituent was synthesized. Upon irradiation in acetonitrile or DMSO with light of 436 nm, they underwent Z–E isomerization of the C=C bond, followed by very fast N→O migration of the acyl group and the formation of nonemissive O-acylated isomers. These isomers were isolated preparatively and fully characterized by IR, 1H, and 13C NMR spectroscopy as well as HRMS and XRD methods. The reverse thermal reaction was catalyzed by protonic acids. N-Acylated compounds exclusively with Fe2+ formed nonfluorescent complexes with a contrast naked-eye effect: a color change of the solutions from yellow to dark orange. Subsequent selective interaction with AcO− led to the restoration of the initial absorption and emission properties. Thus, the obtained compounds represent dual-mode “on–off–on” switches of optical and fluorescent properties under sequential exposure to light and H+ or sequential addition of Fe2+ and AcO− ions

Reaction of quinaldine with 4,6-di(tert-butyl)-3-nitro-1,2-benzoquinone. Dependence of the outcome on the reaction conditions and a deeper insight into the mechanism

Condensation of quinaldine with 4,6-di (tert-butyl)-3-nitro-1,2-benzoquinone results in the formation of 5,7-di (tert-butyl)-2-(quinoline-2-yl)-1,3-tropolone, 5,7-di (tert-butyl)-4-nitro-2-(quinoline-2-yl)-1,3-tropolone, 3,3-dimethyl-2-(5-hydroxy-4-nitro-3-tert-butyl-6-quinoline-2-yl-pyridine-2-yl)butanoic acid, 6-(2,2-dimethylprop-3-yl)-5-tert-butyl-4-nitro-2-(quinoline-2-yl)-pyridine-3-ol, 1,7-di (tert-butyl)-3-(quinoline-2-yl)-2-azabicyclo-[3.3.0]octa-2,7-diene-4,6-dione-N-oxide. The formation of 1,3-tropolone and pyridine-2-yl butanoic acid derivatives proceeds through a ring expansion and 2-azabicyclo [3.3.0]octa-2,7-diene-4,6-dione-N-oxide via the contraction of the o-quinone ring. The structure of the heterocyclic compounds obtained was justified by X-ray diffraction analysis, NMR spectroscopy, IR- and HRMS-spectrometry, and the proposed mechanisms of their formation include the participation of an intermediate product of the expansion reaction of the o-quinone cycle - 5,7-di (tert-butyl)-4-nitro-2-(quinoline-2-yl)-cyclohepta-1,3,5-triene-1,3-diol, which was first isolated preparatively. The DFT/B3LYP/6–311++G** methods were used to determine the thermodynamic stability of tautomeric forms of intermediate products, as well as the relative stability of NH and OH tautomers of 5,7-di (tert-butyl)-2-(quinolin-2-yl)-1,3-tropolone and 5,7-di (tert-butyl)-4-nitro-2-(quinolin-2-yl)-1,3-tropolone