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Capturing Conformation‐Dependent Photoreactivity of Crystalline 3‐Azido‐1,3‐diphenylisobutyrophenone
Author(s) -
Karthik Sambath,
ThennaHewa Kosala R. S.,
Shields Dylan J.,
Liu Jinhao,
Krause Jeanette A.,
Gudmundsdottir Anna D.
Publication year - 2017
Publication title -
chemphotochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.13
H-Index - 18
ISSN - 2367-0932
DOI - 10.1002/cptc.201700081
Subject(s) - azide , chemistry , conformational isomerism , crystal structure , benzonitrile , photochemistry , density functional theory , excited state , moiety , ketone , crystallography , ground state , bond cleavage , stereochemistry , computational chemistry , molecule , medicinal chemistry , organic chemistry , catalysis , physics , quantum mechanics , nuclear physics
Solid‐state photolysis of 3‐azido‐1,3‐diphenyl‐isobutyrophenone 1 results in selective formation of isobutyrophenone 2 and benzonitrile 3 . X‐ray structure analysis of azide 1 demonstrates that the conformer ( 1Cr ) adopted for packing in the crystal lattice has the carbonyl moiety perpendicular to the α‐phenyl group (Ph‐C=O torsional angle of 85°). Laser flash photolysis of azide 1 nanocrystals allows direct detection of the lowest excited triplet ketone (T K ) of 1Cr ( λ max ≈475 nm). Thus, in crystals, 1 is proposed to react via the T K state to cleave the Cβ−Cγ bond. Time‐dependent density functional theory (TD‐DFT) calculations verify that the energy of the T K of 1Cr is 79 kcal mol −1 above the ground state (S 0 ), and thus T K has sufficient energy for cleavage of the Cβ−Cγ bond to form products 2 and 3 , further supporting this solid‐state reaction mechanism.