Spectroscopic studies of the multiporphyrin arrays at the air-water interface and in Langmuir-Blodgett films

We describe the spectroscopic studies of the monolayers and Langmuir-Blodge tt (LB) films of tetrapyridylporphyrin (TPyP), its mixture with a phospholi pid (DPPTE) and the (2DPPTE-)Cd2+-TPyP multiporphyrin arrays. Red-shift of the porphyrin Soret band was 23-27 nm in the monolayers and LB films of TPy P or the TPyP-2DPPTE mixtures while it was only 3-11 mn in the monolayers a nd LB films of the (2DPPTE-)Cd2+-TPyP multiporphyrin arrays. This differenc e has been attributed to the weakened TPyP-TPyP interaction in the multipor phyrin arrays. Immersion of an intercalation phospholipid layer in the matr ix of the monolayers and LB films of TPyP or the Cd2+-TPyP multiporphyrin a rray further reduced this interaction and made it possible for the fabricat ion of three-dimensional layered multiporphyrin arrays. The fluorescence sp ectra of TPyP in the LB films of the (2DPPTE-)Cd2+-TPyP multiporphyrin arra y were also quite different from those in the solutions and TPyP(-2DPPTE) L B films. The average molecular orientation angle theta between the mean por phyrin plane and the substrate surface was approximately 26-31 degrees for the LB films of the TPyP and the Cd2+-TPyP multiporphyrin array, and approx imately 35-38 degrees for the LB films of the TPyP-2DPPTE and 2DPPTE-Cd2+-T PyP multiporphyrin array. (C) 2001 Elsevier Science B.V. All rights reserve d.