Synthetic strategies and basic molecular principles were investigated in order to achieve chromophores absorbing light in the far red or even near infrared region. Therefore, a comprehensive series of new squaraine dyes were synthesized and characterized. Beside monomeric unsymmetrical and symmetrical squaraine dyes, also squaraine dye dimers and oligomers bridged with phenylene, fluorene, iso-octyloxy phenylene and tetrafluoro ...
