| Abstract: A new series of dimeric porphyrins with two amide groups linkage and the corresponding platinum(Ⅱ) complexes were synthesized by the amidation of ethylenediamine, 1,3-diaminopropane and 1,4-diaminobutane with 5-(4-carboxy-phenyl)-10,15,20-tri-(4-dodecyloxyphenyl) porphyrin (HAcTPP) and characterized by 1H NMR, 13C NMR, MS, elemental analysis, cyclic voltammetry, UV-Vis and fluorescent spectrometer. It is found that photoluminescence (PL) spectra for the dimers show concentration dependences. In dilute solution (10-7 mol·L-1), maxima of PL peak for dimers was located at 657 nm, which has identical PL peak with single porphyrin, HAcTPP. When concentration was increased to 10-3 mol·L-1, the maximal PL peak value (675 nm) for the dimeric porphyrins exhibited 18 nm bathochromic shift (relative to single porphyrin, HAcTPP). Moreover, the concentration dependence PL spectra become more sensitive for dimeric complexes that were obtained by refluxing dimeric porphyrin with PtCl2 in benzonitrile solution. The maximal PL peak values (about 673 nm) for dimers complexes showed 16 nm red-shifts compared with that for HAcTPP even in 10-7 mol·L-1 dilute THF solution. With concentration increase to 10-4 mol·L-1, the emission peak for complexes of dimeric porphyrin was at 727 nm, which is red-shifted to near-infrared range. To examine the correlation between the luminescence and intermolecular π-π and/or Pt(Ⅱ)-Pt(Ⅱ) interactions for the dimeric complexes, the solid-state luminescence for the dimeric complex, Pt2C3(AmTPP)2, at room temperature and 77 K was measured, which showed low-energy emissions with a maximum at 658 nm at room temperature. Upon cooling the solid sample to 77 K, the solid sample exhibited red-shift of 16 nm (from 658 to 674 nm) and there was more structured spectrum with an additional weak emission at 706 nm. Furthermore, sublimating films of the complexes also yielded red-shift emission at about 727 nm and broadened PL profile with an additional tailing at 760~810 nm, which would account for more intensive π-π interaction and/or Pt(Ⅱ)-Pt(Ⅱ) interaction in sublimating films. |
