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Mechanistic Investigation on Chemiluminescent Formaldehyde Probes
Author(s) -
Pi Shuangqi,
Li Quansong,
Yue Ling,
Liu YaJun
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202004556
Subject(s) - dioxetane , chemiluminescence , chemistry , singlet state , formaldehyde , derivative (finance) , density functional theory , photochemistry , decomposition , combinatorial chemistry , computational chemistry , organic chemistry , excited state , physics , nuclear physics , financial economics , economics
A first‐generation pair of chemiluminescent formaldehyde (FA) probes (CFAP540 and CFAP700) was reported recently. CFAP540 and CFAP700, with high selectivity and sensitivity to FA, are, respectively, suitable in cell and in vivo. Experimentalists have confirmed that both probes utilize a general 2‐aza‐Cope FA‐reactive trigger and a chemiluminogenic phenoxydioxetane scaffold. The mechanism and detailed process of CFAP chemiluminescence (CL) remain largely unknown. In the present paper, (time‐dependent) density functional theory calculations are performed on the entire reaction process of CFAP540 with FA to produce CL. The calculations elucidated the CL‐producing process: FA initiates the decomposition of CFAP540 by dehydration condensation, and a phenoxy 1,2‐dioxetane is formed through a series of reactions of aza‐Cope rearrangement, hydrolysis of imine, and β‐elimination of alkoxyl group. Afterwards, the produced phenoxy 1,2‐dioxetane decomposes to produce the m ‐oxybenzoate derivative in the first singlet state (S 1 ) via two crossings between potential energy surfaces of the ground state (S 0 ) and S 1 state. This m ‐oxybenzoate derivative was assigned as the light emitter of the CFAP540 CL. The CL‐producing process and assignment of the light emitter of CFAP700 CL are similar with the corresponding ones of CFAP540. By analyzing the D‐π‐A architecture of the light emitters of CFAP540 and CFAP700, a series of CFAPs is theoretically designed and a scheme to modulate their CL from visible to near‐infrared region is proposed by adjusting the length and structure of the π‐bridge.