During the process of developing organic molecules that match the wavelengths used in optical communications, we have discovered a new class of dyes, with absorption maxima at 1.1 mum, and clarified their molecular structures. The synthesis of this class of dyes was supposed to involve unexpected intramolecular tandem reactions, and the effect of alkyl substituents on such a synthesis was investigated. As a result, an effective alkyl-substituent structure for realizing a high synthetic yield and good solubility in organic solvents was found. Furthermore, thin films made of such a highly soluble dye were fabricated by solution-coating, and they exhibited a red-shifted absorption band with a maximum at approximately 1.3 mum, indicating the formation of J-like aggregates. The third-order nonlinear optical susceptibility chi(3) of these thin films at 1.3 mum, which is the wavelength used in optical communications, was measured by the Z-scan technique. The magnitude of chi(3) reaches approximately 10-7 esu. These results suggest that the solution-coated thin films of this type of dye are potential materials for optical switching at 1.3 mum and for other nonlinear optical applications.