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1,4‐Naphthoquinonediazide‐2‐carboxylic acid: a diazo compound with a long‐lived triplet excited state
Author(s) -
Bucher Götz,
Wandel Holger,
Sander Wolfram
Publication year - 2001
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.354
Subject(s) - chemistry , excited state , diazo , phosphorescence , flash photolysis , triplet state , photochemistry , naphthalene , moiety , carboxylic acid , computational chemistry , molecule , stereochemistry , medicinal chemistry , atomic physics , organic chemistry , fluorescence , reaction rate constant , kinetics , physics , quantum mechanics
Laser flash photolysis (308 nm) of 1,4‐naphthoquinonediazide‐2‐carboxylic acid 1 in 2‐methyltetrahydrofuran (MTHF) leads to the detection of a long‐lived (5.3 μs) triplet excited state, whose triplet energy, obtained by measuring the phosphorescence spectrum of 1 in an Ar‐ matrix at 10 K, is ca 55 kcal mol −1 (1 kcal= 4.184 KJ). The first triplet excited state of 1 is quenched efficiently by 1,3‐dienes and molecular oxygen. By calculating the spin density distribution it can be shown that 3 1 is not a typical naphthalene triplet, as it bears significant spin density at the diazo moiety. Copyright © 2001 John Wiley & Sons, Ltd.