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

Abstract

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

“…According to data previously obtained [14], the signals of methine protons of E-isomers should be in the region of approximately 5.90 ppm [14]. Other IR, 1 Н and 13 С NMR spectroscopy and HRMS data confirming the structure of the synthesized compounds 1 and 2a-c are presented in Supporting Information File 2.…”

“…The colorless solids 3a (80%), 3b (75%) and 3c (85%), respectively, gradually precipitated. For the first time in the course of studying N→O acylotropic migrations, photorearrangement products 3a-c were comprehensively characterized by IR, 1 Н and 13 C NMR spectroscopy, HRMS (Supporting Information File 2)…”

“…For most photochromic compounds, irradiation of the solution or solid results in a deepening of the color (positive photochromism). Less studied are those characterized by photoinduced bleaching (negative or inverse photochromism), such as merocyanine forms of spiropyrans and spirooxazines, azomethine imines, thioindigoid dyes and N→O acylotropic systems [12][13][14][15]. Recently, they have been actively used to create next-generation molecular switches, materials with new properties (in particular, color change depending on the intensity of sunlight), photochromic tags for biological research and optical sensors [15][16][17][18][19][20][21].…”

Ground-State Tautomerism and Excited-State Proton Transfer in 7-Hydroxy-4-methyl-8-((phenylimino)methyl)-2H-chromen-2-one as a Potential Proton Crane

“…Excited-state intramolecular proton transfer (ESIPT) is a feature of organic molecules, containing strong proton-donating/accepting groups, which, due to the increased acidity/basicity in the excited state, exchange a proton over the short distance of pre-existing hydrogen bonding [1][2][3][4][5][6][7][8][9][10]. ESIPT-exhibiting molecules have become a field of active research in recent decades, due to their applications as light-emitting materials and laser dyes [11][12][13][14][15], optical sensors [16][17][18][19][20][21][22][23][24][25][26][27], organic light-emitting diodes [20,21,[28][29][30][31][32][33][34][35][36], optical storage devices [37] and photo stabilizers [38]. The same process underlies a special class of bistable photo switches [39], called proton cranes, where the ESIPT is accompanied by intramolecular rotation [40], leading to the transport of a movable proton from one side of the molecule to another.…”

3-Pyrazolines (2,3-dihydro-1H-pyrazoles): synthesis, reactivity, and physical and biological properties

“…). Several authors have studied the 64/65 relationship in Scheme 22 between pyrazolidinones and diazabicyclohexanones 76,77. …”