Systematic Molecular Engineering of a Series of Aniline-Based Squaraine Dyes and Their Structure-Related Properties

Document Type

Article

Publication Date

2-22-2018

Abstract

With the objective of developing new near-infrared fluorescent probes and understanding the effect molecular structure exerts on physical properties, a series of aniline-based squaraine dyes with different number and position of methoxy substituents adjacent to the squaraine core were synthesized and investigated. Using both computational and experimental methods, we found that the subtle changes of the number or position of the methoxy substituents influenced the twisting angle of the structure and led to significant variations in optical properties. Moreover, the methoxy substituent also affected aggregation behavior due to steric effects. The X-ray crystal structure of one of the key members of the series, SD-2a, clearly demonstrates the distortion between the four-membered squaraine core and the adjacent aniline ring due to methoxy substitution. Structure-related fast relaxation processes were investigated by femtosecond pump-probe experiments and transient absorption spectra. Quantum chemical calculations and essential state models were exploited to analyze the primary experimental results. The comprehensive investigation of structure-related properties of dihydroxylaniline-based squaraine dyes, with systematic substitution of OH by OCH3 functional groups, serves as a guide for the design of novel squaraine dyes for photonics applications.

Identifier

85042536521 (Scopus)

Publication Title

Journal of Physical Chemistry C

External Full Text Location

https://doi.org/10.1021/acs.jpcc.7b11997

e-ISSN

19327455

ISSN

19327447

First Page

3994

Last Page

4008

Issue

7

Volume

122

Grant

CHE-0832622

Fund Ref

European Commission

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