Papers by Keyword: TPPS

Abstract: In order to investigate the chiral interfacial assembly of special amphiphile, a trigonal Schiff base compound with long alkyl chains was designed and synthesized, and its supramolecular assembly and interaction properties were investigated by spectral and morphological measurements. Condensed monolayers were obtained on pure water surface, in which flat and uniform domains were obtained for the monolayers. When an anionic tetrakis(4-sulfonatonphenyl)porphine (TPPS) was added into an acidic subphase, an in situ complex formation between the trigonal amphiphile and TPPS occurred. The complex monolayers were transferred onto solid substrate and TPPS existed as J-aggregate and J-aggregate in the complex films. Due to the multisited positive charges in the spacer on acidic subphase, the complex films of trigonal amphiphile with TPPS appeared as short nanorod structures and formed two-dimensional (2D) conglomerate chiral domains.

Abstract: The mechanism and conditions of meso-tetra (4-sulfonatophenyl) porphine (TPPS₄) molecular aggregate formation and their geometrical structure are investigated by methods of molecular mechanics and quantum chemistry. J- type aggregates are formed of zwitterionic forms of TPPS₄ via interaction of their positively charged porphyrin rings and negatively charged SO₃ - groups. According to ab initio and PM3 calculations it was found that TPPS₄ zwitterion has asymmetrical structure (parts of porphyrin ring are asymmetrically bent out of plane), although the porphyrin ring of TPPS₄ molecule in neutral aqueous solution (at pH 7) is flat and the planes of phenyl rings are nearly perpendicular to the porphyrin plane. We propose that asymmetrical porphyrin rings are able to form bent threads. The thread is bent approx. 5° for each monomer, so approximately 60 monomers should form the loop (diameter ~20 nm).

Abstract: An understanding of both the interactions between the adsorbate molecules and the interactions between adsorbates and the surface is a prerequisite to eventually controlling the selfassembly process in supramolecular aggregation. Here we report the formation of supramolecular structures (J-aggregates) whose size and aggregation pattern are controlled by changing the number of polar sulfonic groups of meso-tetra (4-sulfonatophenyl) porphine. Using atomic force microscopy we show that substituted porphyrin molecules (5,10,15,20-tetrakis(4-sulfonatophenyl) porphine (TPPS₄), 5,10,15-tris(4-sulfonatophenyl)-20-phenyl porphine (TPPS₃), 5,15-bis(4-sulfonatophenyl)- 10,20-diphenyl porphyne (TPPS_2op) - SO₃ groups are opposite each other, and 5,20-bis(4- sulfonatophenyl)-10,15-diphenyl porphyne (TPPS2a) . SO₃ groups are adjacent each other) form different spatial structures. Our findings suggest that placement of functional groups that are participating in direct noncovalent interactions will allow design and construction of different supramolecular structures adsorbed to surfaces.

Abstract: The adsorption of organic molecules on solid surfaces is one of the fundamental processes for the development of molecular-based nanodevices. Here we focus on the adsorption and ordering of the TPPS₄-based J-aggregates on silicon and gold as well as on self-assembled monolayer (SAM) surfaces. The SAMs used for the experiments were based on the chemisorption of thiol containing compounds onto gold. Long ω-substituted alkanethiols are spontaneously assembled on gold to form highly ordered and densely packed layers with controllable chemical and physical properties. TPPS₄ J-aggregates were dispersed on SAM surfaces, and on plain gold and silicon substrates for comparison. The dimensions of aggregates, measured by means of atomic force microscopy, varied depending on the type of substrate. Long stripe-like aggregates were flattened on the substrate surface, and the height and width of aggregates highly correlated with the polarity of surface groups. For example, the J-aggregates were narrower on hydrophobic substrates (with non-polar groups) and wider on hydrophilic substrates (with polar groups). These observations support the hypothesis, that TPPS₄ forms .soft. cylindrical aggregates, that appear flattened on the substrate.