Organization of a New Tetraalkynyl Porphyrin by the Langmuir−Blodgett Technique

Abstract

A new tetraalkynyl porphyrin: the meso-tetra(trimethylsilylethynyl)-β-tetra(acetic acid)porphyrin, abbreviated as H2P1, has been synthesized and organized by the Langmuir−Blodgett technique. When spread alone on pure water, it spontaneously stacks in a herringbone manner. Different methods have been used to break the π−π interactions and favor a flat-on anchoring of the macrocycle onto the water surface. Stable Langmuir and Langmuir−Blodgett films have been thus obtained and characterized by UV and IR spectroscopies and X-ray diffraction. A first method consists in introducing divalent cations into the subphase. It leads to an almost planar arrangement with a tilt angle of the macrocycle of ca. 15°. Another approach consisting in mixing a H2P1/tricosylamine complex with methyl eicosanoate was also tried. An optimal proportion of 1:4:10 was found, leading to a tilt angle of ca. 25°.

Meso-Tetra-Alkynyl Porphyrins for Optical Limiting—A Survey of Group III and IV Metal Complexes

“…However, use of the more robust triisopropylsilyl (TIPS) protecting group overcame this problem, in every case except for silicon; all attempts at inserting silicon into the free-base porphyrin H 2 1 resulted in either no reaction or destruction of the porphyrin. [14] This crystal structure also shows the undistorted planar virtual D 4h geometry of these porphyrins, [7,15] which contributes towards their sharp absorption spectra; all 24 atoms of the macrocycle are within 0.2 of their mean plane. All these complexes gave clean 1 H and 13 C nuclear magnetic resonance (NMR) spectra and satisfactory elemental analyses and mass spectra.…”

Electrochemical properties of protoporphyrin IX zinc(II) films

“…The organization of porphyrins and their intentionally designed derivatives on solid substrates is of current interest due to their important roles in making functional materials and devices, such as catalysts [1] and sensors [2], and also as a model for some biochemical processes [3][4][5]. In particular, mono-or multilayer films of porphyrins may provide not only a template for their catalytic and biopolymer-binding properties but also a component in molecular devices.…”

Langmuir−Blodgett Mixed Films of Titanyl(IV) Pthalocyanine and Arachidic Acid. Molecular Orientation and Film Structure

“…The increasing of the area per molecule in mixed Langmuir films with AA has also been observed in Langmuir monolayers of materials presenting a high degree of stacking. 29,30 The unexpected increase in area per molecule in the mixed film continues up to 1:4 (TiOPc-AA) molecular ratio, providing the largest mixed monolayer expansion, as seen in Figure 2. The area per molecule of the 1:4 mixed Langmuir monolayers was found to be 82 Å 2 .…”

“…The area per molecule of the 1:4 mixed Langmuir monolayers was found to be 82 Å 2 . Following the interpretation put forward by Da Cruz et al, 30 the fatty acid seems to fill in the space available between the macrocycles, preventing molecular stacking and facilitating a planar orientation of the Pc's. The assumption that TiOPc molecules might be lying flat on the water subphase is supported by the results extracted from the RAIRS analysis of the LB films (vide infra).…”