Wavelength-dependent switching of the photocurrent direction at the surface of molecular semiconductor electrodes based on orbital-confined excitation and transfer of charge carriers from higher excited states

Electrostatic self-assembly layer-by-layer film fabrication using a polycation and a phthalocyanine dye anion

A multi-layer film has been fabricated, using poly(diallyldimethylammonium chloride) ( PDDAC ) and a copper phthalocyanine ( CuPc ) dye, held together by electrostatic forces and layer-by-layer self-assembly attractions. The result of the multi-layer fabrication was characterized by UV-vis absorbance measurements and Atomic Force Microscopy (AFM). UV-vis absorption spectra of the multi-layer films increased linearly at 676 nm, which indicated that the fabrication proceeded regularly. The AFM images show that the surface of the self-assembled multi-layer was thickly covered with PDDAC / CuPc and relatively uniform.

Spectroscopy and electronic structure of electron deficient zinc phthalocyanines

The effect of introduction of perfluoro alkyl groups into phthalocyanines, as evidenced by the spectroscopic properties of 1,4,8,11,15,18,22,25-octa-fluoro-2,3,9,10,16,17,23,24-octa-perfluoro isopropyl zinc phthalocyanine, ZnF(64)Pc(-2) and its ring-reduced radical anion species, [ZnF(64)Pc(-3)](-), are reported. A combination of UV-visible absorption and magnetic circular dichroism (MCD) spectroscopy, ESI and MALDI-TOF mass spectrometry, cyclic and differential pulse voltammetry, and complete theoretical calculations using INDO/S and DFT techniques reveals that the substitution of all sixteen hydrogen atoms in protio ZnPc(-2) by eight F and eight i-C(3)F(7) groups red shifts the Q and pi --> pi transitions and narrows the HOMO-LUMO gap while simultaneously preventing ring photooxidation and stabilizing the radical anion. The [ZnF(64)Pc(-3)](-) species, which is in equilibrium in solution with the neutral complex when a reducing agent is present, is unusually stable. The above effects are attributed to the strong electron withdrawing properties of the peripheral substituents, which render ZnF(64)Pc extremely electron deficient.