LAUSR

Abstract Cyanine dyes are interesting compounds for diverse technological applications mainly because of their unique optoelectronic properties. Despite their interesting features, in general, structural and optical properties of these materials are not well described by electronic structure calculations. In this report distinct approaches and methods were used to evaluate structural and optical properties of a series of cyanine dyes to identify suitable methodologies. The results suggest that polymethine dyes can be properly modeled as cationic structures and non-conventional AM1/CIS and PM3/CIS approaches can describe the major optical features of these compounds, due a better description of the electron density on the carbon chains. Our data indicate very suitable and inexpensive approaches to investigate new cyanine dyes.