Magnesium Porphine Supermolecules and Two-Dimensional Nanoaggregates Formed Using the Langmuir–Schaefer Technique

Abstract

Porphyrins are functional elements of important biomolecules, whose assemblies play a central role in fundamental processes such as electron transfer, oxygen transport, enzymatic catalysis, and light harvesting. Here we report an approach to formation of porphyrin supermolecules, a particular type of nanoparticles with unusually strong noncovalent intermolecular interactions. Key differences between the supermolecules and noncovalent nanostructures described earlier are as follows. (1) Supermolecules consist of molecules of the same type without side groups promoting the self-assembly and without any spacers; no surfactant or catalyst to assist the process is needed. (2) They exhibit unusual photophysical properties and remain stable even in organic solvents. Their formation occurs under specially selected conditions at the air-water interface at room temperature. Following this route, we have formed supermolecules of magnesium porphine, a functional element of chlorophyll. The properties of these supermolecules are markedly different from those of the constituent molecules. For example, in contrast to the pink color of the monomer solution, solutions of supermolecules are transparent for visible light and absorb in the ultraviolet and near-infrared regions. We also present atomic force microscopy visualization of the porphyrin two-dimensional nanoaggregates forming at the air-water interface that were predicted in our previous works. This approach offers a guideline for the discovery of new supermolecules, including complex biological ones, and the formation of supermolecular materials with novel properties.

An Influence of Copper Cation in the Complex on Structure of the Nanostructured Layers, Spectral and Electrocatalytic Characteristics of Langmuir-Schaeffer Films of Triphenylcorrole

“…It is shown that nanoaggregates of the complex more dense than nanoaggregates of the ligand (Figure 5a). The number of molecules in Cu[(ms-Ph) 3 Cor] aggregates more than the number of molecules in H 3 [(ms-Ph) 3 Cor] aggregates (by 2-3 times, Figure 5b). The rate of change the number of molecules in face-on and edge-on nanoaggregates with increasing of the initial surface coverage degree is 2-3 times greater for the complex than for the ligand (Figure 5b).…”

“…The state of the Cu[(ms-Ph) 3 Cor] layer at the point A corresponds to «edge-on bilayer -tetralayer» (samples I and II, Figure 7). The state of the H 3 [(ms-Ph) 3 Cor] layer at the point B corresponds to «edge-on tetralayer» (sample III, Figure 7). (sh sol) = 1.9.…”

“…Face-on and edge-on monolayers of the copper complex, unlike the ligand, are stable only at very low pressures (up to 0.4-0.5 mN/m). At high initial surface coverage degree under same conditions, the complex with copper forms bilayers, unlike H 3 [(ms-Ph) 3 Cor] which forms tetralayers. The surface coverage degree by M-aggregates at the initial point of a stable state of copper triphenylcorrole, as well as the ligand, does not depends on the initial surface coverage degree and the arrangement of molecules in the aggregates.…”

“…To obtain the floating layers the solution of Cu[(ms-Ph) 3 Cor] in dichloromethane (C=1.2·10 -4 M) was applied onto the surface of bidistilled water with a microliter syringe (Hamilton, Sweden) at the temperature of 20±1 °C. The volume of the solution to be applied was determined according to the required initial surface coverage degree (c face ), i.e.…”

“…Macroheterocyclic compounds are able to form organic nanostructures due to the self assembly. [1][2][3][4] Self-assembly of porphyrins and related compounds is one of the dominant concepts in the development of functional systems based on this class of compounds. [5][6][7] The creation of thinfilm of organic materials, consisting of two-and threedimensional nanoparticles is of great interest.…”