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Synthesis and Electronic Properties of 1,2‐Hemisquarimines and Their Encapsulation in a Cucurbit[7]uril Host
Author(s) -
De Filippo Christian C.,
Tang Hao,
Ravotto Luca,
Bergamini Giacomo,
Salice Patrizio,
Mba Miriam,
Ceroni Paola,
Galoppini Elena,
Maggini Michele
Publication year - 2014
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.201400039
Subject(s) - photochemistry , chromophore , excited state , molar absorptivity , protonation , fluorescence , chemistry , aniline , materials science , optoelectronics , organic chemistry , optics , atomic physics , ion , physics
The synthesis of a new class of robust squaraine dyes, colloquially named 1,2‐hemisquarimines (1,2‐HSQiMs), through the microwave‐assisted condensation of aniline derivatives with the 1,2‐squaraine core is reported. In CH 3 CN, 1,2‐HSQiMs show a broad absorption band with a high extinction coefficient and a maximum at around λ =530 nm, as well as an emission band centered at about λ =574 nm, that are pH dependent. Protonation of the imine nitrogen causes a redshift of both absorption and emission maxima, with a concomitant increase in the lifetime of the emitting excited state. Encapsulation of the chromophore into a cucurbit[7]uril host revealed fluorescence enhancement and increased photostability in water. The redox characteristics of 1,2‐HSQiMs indicate that charge injection into TiO 2 is possible; this opens up promising perspectives for their use as photosensitizers for solar energy conversion.