Cyclopentene ring effects in cyanine dyes: a handle to fine-tune photophysical properties

• Published in: Physical chemistry chemical physics : PCCP Vol. 26; no. 7; pp. 6235 - 6241
• Main Authors: Neme, Natália, Jansen, Thomas L. C, Havenith, Remco W. A
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 14.02.2024; The Royal Society of Chemistry
• Subjects: Chemistry; Cyanine dyes; Cyclopentene; Density functional theory; Dyes; First principles; Molecular orbitals
• ISSN: 1463-9076; 1463-9084; 1463-9084
• DOI: 10.1039/d3cp05219b

The aim of this study is to investigate the photophysical properties of a cyanine dye analogue by performing first-principles calculations based on density functional theory (DFT) and time dependent-DFT. Cationic cyanine dyes are the subject of great importance due to their versatile applications and the tunability of their photophysical properties, such as by modifying their end groups and chain length. An example of this is the vinylene shift, which is experimentally known for these molecules, and it consists of a bathochromic (red) shift of approximately 100 nm of the 0-0 vibronic transition when a vinyl group is added to the polymethine chain. Our study shows that when the saturated moiety C 2 H 4 of the cyclopentene ring is added to the chain, it interacts with the conjugated π-system, resulting in a smaller HOMO-LUMO gap. Here, we demonstrate the origin of this interaction and how it can be used to fine tune the absorption energies of this class of dyes. The aim of this study is to investigate the photophysical properties of a cyanine dye analogue by performing first-principles calculations based on density functional theory (DFT) and time dependent-DFT.