Intramolecular Hydrogen Bonding in a Triangular Dithiazolyl‐Azaindole for Efficient Photoreactivity in Polar and Nonpolar Solvents

Abstract

A triangular dithiazolyl-azaindole derivative has been synthesized as a highly sensitive photochromic molecule. 2,4-Dimethyl-5-phenylthiazol derivative 1a, and a reference compound, 5-methyl-2-phenylthiophene derivative 2a, both showed photochromism with quantum yields of 90 and 45 %, respectively, in hexane, and 90 and 35 %, respectively, in methanol. In the single-crystal state, 1a revealed photochromic coloration. Its conformation was assigned to a photoreac-

Photochromic Dithienylethene‐Containing Boron(III) Ketoiminates: Modulation of Photo‐Responsive Behavior through Variation of Intramolecular Motion

“…More interestingly, modulations of the photochromic behavior through the utilization of different stimuli have been accomplished in the past decades . With an understanding of the fundamentals of the chemical structures and the intrinsic characteristics of photo‐responsive materials, initially suppressed or blocked photochromic properties may be restored by appropriate approaches, including control of the rigidity of the molecule,,,, modification of the molecular structure,–, addition of acids and bases,, or the suppression of radiative decay processes ,…”

Exploring the Conformational Space of Bridge‐Substituted Dithienylcyclopentenes

“…Thus we used in addition to the established (CLIP)-HSQC [64] and HETLOC [65,66] experiments, the J-modulated 1,1-ADEQUATE [67,68] experiment for the determination of one-bond carbon-carbon couplings. Due to the low natural abundance of 13 Ca nd the challengingm easurements in anisotropic environments, there are very few examples of RDC analyses making use of these couplings in non-isotopically labeled small molecules. [69,70] To the best of our knowledget his is the first application of the J-modulated 1,1-ADEQUATEe xperiment in anisotropic media.…”

“…[4][5][6][7][8][9] However,t he already superior switching efficiency still needs to be improved for non-academic applicationsdemanding basically infinite switching cycles,t hat is,h igh fatigue resistance andl arge photocyclization quantumy ields (F oc ). [10][11][12][13][14][15] We recently established as ynthetic protocol for the bridge-substitution of dithienylcyclopentenes and recorded as ignificant increasei nt he F oc value for the substituted derivatives 1-4 (Scheme 1). [16] As it is generally believed that the distribution between the anti-parallel (a-p) and parallel (p) conformations correlates to the F oc value due to the Woodward-Hoffmann rules, [4] it is reasonablet or ationalize the underlying driving force by determinationo ft he fractiono fa -p conformers in the ring-opened form.I nexpediently and as opposed to benzothiophene-substituted DAEs, direct measuremento ft his fraction is analytically very demanding for dithienylcyclopentenes if simple freezing of the conformational isomerst hrough variable-temperature 1 HNMR spectroscopy [10,11,16] does not lead to unambiguous results or if there is more than one a-p conformation involved.…”

Cyclization Dynamics and Competitive Processes of Photochromic Perfluorocyclopentene Dithienylethylene in Solution

“…[13,14] During the last decades, the quantum yield of carbon-carbon photoelectrocyclization limited to 0.5 was a subject of interest explained in term of coexistence of two OF isomers having parallel (P) and anti-parallel (AP) conformations in equal proportions but only the latter being photoactive. [16,17] To overpass such limitation some researchers focused their efforts on exploring purposed-designed synthetic approach [18][19][20][21] or specific excited-state reactivity. [22,23] Indeed, the rationalization of complex excited state mechanisms are highly desired to still improve photochromic performances and so considerable investigations have been devoted worldwide to explore the excited state topologies of DTEs (or DAEs) via advanced optical spectroscopies [24][25][26][27] and/or computational chemistry.…”