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ENERGY TRANSFER‐ENHANCED CHEMILUMINESCENCE OF ADAMANTANONE ( n ,π*) AND ESTER (π,π*) SINGLET AND TRIPLET EXCITED STATES IN THE THERMOLYSIS OF SILYLOXYARYL‐SUBSTITUTED SPIROADAMANTYL DIOXETANES †
Author(s) -
Trofimov Alexei V.,
Vasil'ev Rostislav F.,
Mielke Karsten,
Adam Waldemar
Publication year - 1995
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1995.tb05235.x
Subject(s) - chemistry , singlet state , excited state , photochemistry , singlet fission , triplet state , chemiluminescence , dioxetane , phosphorescence , quantum yield , fluorescence , atomic physics , molecule , organic chemistry , physics , quantum mechanics
— The thermal generation of singlet and triplet excited states from silyloxyaryl‐substituted spiroadamantyl dioxetanes lab and the adamantylidineadamantane dioxetane (1c) was investigated by direct and enhanced chemiluminescence (CL). 9,10‐Diphenylanthracene (DPA) and 9‐fluorenone were used as energy acceptors in the singlet‐singlet (S‐S), naphthalene and europium chelate Eu(TTA) 3 Phen (TTA = thenoyltrifluoroacetone, Phen = 1,10‐phenanthroline) in the triplet‐triplet (T‐T) and 9,10‐di‐bromoanthracene (DBA) in triplet‐singlet (T‐S) energy transfer experiments. The direct chemiluminescence observed in the thermolysis of dioxetanes lab consisted of fluorescence derived from the singlet‐excited adamantanones 2a,b. In the presence of naphthalene, selective T‐S energy transfer with DBA (napthalene as quencher) displayed the adamantanone triplets 2a,b and with Eu(TTA) 3 Phen (naphthalene as mediator) also the silyloxyaryl ester 3 triplets. From the Stern‐Volmer constants ( k TN T T 0 ) the triplet lifetimes t 0 t of these triplet state products were assessed. By using the Hastings‐Weber standard, the total triplet excitation yield (φ t ) was estimated to be ca 20%. The energies of the first excited singlet and triplet states of the adamantanones 2a,b and the silyloxyaryl ester 3, the products of the thermally induced decomposition of dioxetanes la‐c , were determined by semiempirical calculations (AMI‐based configuration interaction), which included explicitly solvent effects on the excitation energies in terms of a self‐consistent reaction field approach. The calculations revealed that the first excited singlet and triplet states of the adamantanones 2a,b are expectedly n ,π*‐type excitations while the silyloxyaryl ester 3 possesses π,π* character. The semiempirical computations suggest that excitation of the adamantanones 2a,b as well as the silyloxyaryl ester 3 is feasible in the thermolysis of the spiroadamantyl dioxetanes lab , which has been confirmed by the experimental energy transfer studies.