Aggregation of thioether-substituted subphthalocyanines with palladium(ii) at the toluene–water interface

Abstract

Novel chloro-subphthalocyaninatoboron(III) (Subpc) derivatives with six thioether at the 2 and 3 positions of peripheral benzene (Subpc(SR)₆) such as chloro-[2,3,9,10,16,17-hexakis-ethylthio-subphthalocyaninato]boron(III) (Subpc(SEt)₆) and chloro-[2,3,9,10,16,17-hexakis-benzylthio-subphthalocyaninato]boron(III) (Subpc(SBz)₆) were synthesized. The interfacial adsorption of Subpc and Subpc(SR)₆, and the interfacial aggregation of Subpc(SR)₆–Pd(II) complexes in the toluene–water system have been investigated by means of high-speed stirring (HSS) spectrometry, centrifugal liquid-membrane (CLM) spectrometry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS). Characteristically orientated structures of Subpc(SR)₆ molecules and the aggregates of Subpc(SR)₆–Pd(II) complexes at the toluene–water interface have been suggested depending on the structures of Et and Bz at the periphery. The interfacial aggregation was observed only in the presence of palladium(II), in which one aggregate unit contained at least seven 1 : 2 complexes of Subpc(SR)₆–Pd(II). Interestingly, the absorption spectra of the interfacial aggregates of Subpc(SEt)₆–Pd(II) and Subpc(SBz)₆–Pd(II) complexes were very similar to the previously reported spectra of μ-oxo dimer and binuclear molecule of subphthalocyanine, respectively, suggesting the formation of “face-to-face” or H-aggregate for Subpc(SEt)₆–Pd(II) and “head-to-tail” or J-aggregate for Subpc(SBz)₆–Pd(II), respectively, at the toluene–water interface.