Spectroscopic Investigations of a Tetrasubstituted Aluminum Naphthalocyanine Near-Infrared Compounds

Abstract

The spectroscopic characteristics in methanol of tetra substituted aluminum 2,3-napthalocyanines (2,3-NcAl) derivatives have been investigated. The tetra substitution of an aluminum naphthalocyanine molecule produces a bathochromic shift of the Q and B band. The N band showed almost no effect by the presence of the functional group and remained at a constant frequency; however, multiple overlapping of bands occurred between 25000 cm⁻¹ (400 nm) and 35000 cm⁻¹ (250 nm). The degree of bathochromic shift of the Q band was affected by the electron withdrawing or electron donating property of the substituents. Changes in the absorption of the Q, B and N band will be discussed. The fluorescence, quantum yield and molar absorptivity of the Q-band due to structural modifications are reported. The molar absorptivity (ε) of the dyes was in the order of 3.5 (log ε); however, higher ε values were obtained with sulphonic groups. Solubility of these compounds in various solvents will be discussed. Possible use of the dye to determine metals and to other cations concentrations will be discussed.

Key Words:

• Near-Infrared
• naphthalocyanine
• fluorescence
• dyes