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

Taihong Liu, Xinglei Liu, Weina Wang, Zhipu Luo, Muqiong Liu, Shengli Zou, Cristina Sissa, Anna Painelli, Yuanwei Zhang, Mikas Vengris, Mykhailo V. Bondar, David J. Hagan, Eric W. Van Stryland, Yu Fang, Kevin D. Belfield

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)3994-4008
Number of pages15
JournalJournal of Physical Chemistry C
Issue number7
StatePublished - Feb 22 2018

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films


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