Supramolecular assemblies based on crown- and phosphoryl-substituted phthalocyanines and their metal complexes in microheterogeneous media

Histamine-bound magnesium porphyrins: diverse coordination modes, inhibitory role in photodegradation of chlorophyll a and antioxidant activity

The neurotransmitter histamine exists in two isomeric forms and could be an interesting ligand due to three nitrogen atoms with the possibility of binding to metals in different ways besides its crucial role in biological systems. However, no metal-histamine interaction is known in the literature. Therefore, two histamine-bound magnesium porphyrins [MgT(4-Cl)PP(hist)2] 1 and [MgT(4-Br)PP(hist)] 2 have been synthesized and structurally characterized. Interestingly, 1 is a hexa-coordinated magnesium porphyrin due to the axial coordination of two histamine molecules via the nitrogen of the aliphatic amino group with the Mg-Nhistamine distance of 2.300 Å, while 2 is penta-coordinated due to the axial coordination of one histamine molecule through the imidazole nitrogen atom with the Mg-Nhistamine distance of 2.145 Å. The diverse coordination modes of this unique ligand are explored for the first time. Theoretical studies at the level of DFT supported the binding of histamine via imidazole nitrogen atoms for complex 2. Histamine-bound magnesium porphyrins are found to be stable against the photodegradation of magnesium porphyrin in the presence of light and oxygen. Freshly isolated chlorophyll a from spinach showed similar resistivity against photodegradation. Moreover, the histamine-bound complexes showed higher antioxidant activity for 1 (92.45%) compared to the free base porphyrin (73.11%) and MgT(4-Cl)PP (75.89%).

Complexation ability of tetrasulfosubstituted cobalt(II) phthalocyanine toward ORF3a protein of SARS-CoV-2 virus

Complex formation processes of tetrasulfosubstituted cobalt(II) phthalocyanine with ORF3a accessory protein of SARS-CoV-2 coronavirus were studied. The interaction of ORF3a protein with SARS-CoV-2 virus with tetrasulfosubstituted cobalt(II) phthalocyanine affords a stable complex in which metallophthalocyanine exists in the monomeric form. The complex formation induces slight changes in the secondary structure of the protein by increasing the fraction of disordered fragments of the polypeptide chain. The photoirradiation of the complex of ORF3a protein of SARS-CoV-2 virus with tetrasulfosubstituted cobalt(II) phthalocyanine leads to the photooxidation of amino acid residues of the protein.

Controlled Self-Assembly of Low-Dimensional Supramolecular Systems Based on Double-Decker Lanthanide Phthalocyaninates

Abstract

Possessing unique physicochemical properties, phthalocyanines are widely used as active components of supramolecular ensembles and nanomaterials. The functional properties of phthalocyanine-based materials are governed by not only the structure of their discotic molecules, but also the character of their intermolecular interactions, which determine both the self-assembly mechanism and the structure of such systems. This review discusses the experimental approaches, which are based on the notions of colloid and coordination chemistry that enable one to control intermolecular interactions in low-dimensional supramolecular ensembles based on phthalocyanines and metallocomplexes thereof. Using double-decker crown-substituted lanthanide phthalocyaninates as an example, it is shown how one- and two-dimensional nanomaterials with different properties can be obtained from the same type of building blocks employing a set of colloid-chemical methods. Such materials are, in particular, capable for controlled absorption of visible light in ultrathin films and can be employed as conducting one-dimensional components of planar elements for organic electronics.