Effect of Branching on the Delayed Fluorescence and Phosphorescence of Simple Borylated Arylamines

Sudhakar Pagidi, Neena K. Kalluvettukuzhy, Pakkirisamy Thilagar

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

A donor-π-acceptor strategy is being well exploited in several fields in view of their robust optical properties. However, the impact of branching in quadrupolar [A-(D)2] and octupolar [A-(D)3] molecules in comparison to parent dipolar (A-D) molecules on the delayed fluorescence and phosphorescence properties is seldom explored. We have presented herein the distinct and contrasting optical properties of a tridurylborane core bearing -NH2 (1-3) and -NMe2 (4-6) donor moieties, wherein the number of donors is increased systematically. Because of propeller molecular architecture, the donor and acceptor are weakly coupled, and the frontier molecular orbitals are spatially localized. All of the compounds show delayed fluorescence under ambient conditions and persistent phosphorescence at low temperature. Solvent-dependent studies and temperature-dependent luminescence measurements established that quadrupolar (2 and 5) and octupolar (3 and 6) compounds underwent symmetry breaking in the excited state. Curiously, delayed fluorescence and phosphorescence spectra are found to be blue-shifted and follow the same trend as the fluorescence upon an increase in the branches. The highest quantum yield was observed for dipolar compounds. Besides, the phosphorescence lifetime decreases with an increase in the number of branches. These interesting experimental observations are further supported by quantum-mechanical calculations.

Original languageEnglish
Pages (from-to)3142-3151
Number of pages10
JournalInorganic Chemistry
Volume59
Issue number5
DOIs
StatePublished - 2 Mar 2020
Externally publishedYes

Bibliographical note

Funding Information:
P.T. thanks the Science and Engineering Research Board (SERB), New Delhi, India, and IISc for financial support. S.P. and N.K.K. thank the SERB, New Delhi, India, for financial support.

Publisher Copyright:
Copyright © 2020 American Chemical Society.

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