Molecular motor-functionalized porphyrin macrocycles

Molecular motors and switches change conformation under the influence of an external stimulus, e.g. light. They can be incorporated into functional systems, allowing the construction of adaptive materials and switchable catalysts. Here, we present two molecular motor-functionalized porphyrin macrocycles for future photo-switchable catalysis. They display helical, planar and point chirality, and are diastereomers, which differ in the relative orientation of the motor and macrocyclic components. Fluorescence, UV-vis, and 1H NMR experiments reveal that the motor-functionalized macrocycles can bind and thread different variants of viologen guests, including a one-side blocked polymeric one of 30 repeat units. The latter feature indicates that the motor systems can find the open end of a polymer chain, thread on it, and move along the chain to eventually bind at the viologen trap, opening possibilities for catalytic writing on single polymer chains via chemical routes.

Making Graphene-type Material via Polymerization of Porphyrin

<p>The synthesis of new graphene-type materials (<i>via</i> polymerization of porphyrin macrocycles) through a simple chemical synthetic pathway (at RT) has been demonstrated. This newly synthesized material can be dispersed in water with an average sheet size of few microns and with single layer thickness. As the porphyrin contains four inner ring nitrogen atoms thus the presented polymeric material will be close analogous of N-doped graphene. Porphyrin as the key component to synthesize layered graphene type continuous 2D structure has never been attempted before. </p> <p> </p>

Making Graphene-type Material via Polymerization of Porphyrin

<p>The synthesis of new graphene-type materials (<i>via</i> polymerization of porphyrin macrocycles) through a simple chemical synthetic pathway (at RT) has been demonstrated. This newly synthesized material can be dispersed in water with an average sheet size of few microns and with single layer thickness. As the porphyrin contains four inner ring nitrogen atoms thus the presented polymeric material will be close analogous of N-doped graphene. Porphyrin as the key component to synthesize layered graphene type continuous 2D structure has never been attempted before. </p> <p> </p>

Weak Interactions and Conformational Changes in Core-Protonated A2- and Ax-Type Porphyrin Dications

Individual chemical motifs are known to introduce structural distortions to the porphyrin macrocycle, be it in the core or at the periphery of the macrocycle. The interplay when introducing two or more of these known structural motifs has been scarcely explored and is not necessarily simply additive; these structural distortions have a chance to compound or negate to introduce new structural types. To this end, a series of compounds with complementary peripheral (5,15-disubstitution) and core (acidification) substitution patterns were investigated. The single-crystal X-ray structures of 18 5,15-diphenylporphyrin, 5,15-diphenylporphyrindi-ium diacid, and related compounds are reported, including the first example of a 5,15-dialkylporphyrindi-ium. Normal-coordinate structural decomposition (NSD) analysis is used for a detailed analysis of the conformation of the porphyrin subunit within the crystal structures. An elongation of porphyrin macrocycles along the C5,C15- axis (B2g symmetry) is observed in all of the free base porphyrins and porphyrin dications; distance across the core is around 0.3 Å in the free base and diacid compounds, and more than doubled in 5,15-dipentylporphyrin and 5,15-dipentylporphyrindi-ium diacid. While the free base porphyrins are largely planar, a large out-of-plane distortion can be observed in 5,15-diphenylporphyrin diacids, with the expected “projective saddle” shape characteristic for such systems. The combination of these two distortions (B2u and B2g) from regular porphyrin structure results in a macrocycle best characterized in the chiral point-group D2. A rare structural type of a cis-hydrogen bond chelate is observed for 5,15-dipentylporphyrindi-ium diacid, which adopts an achiral C2v symmetry. Crystallographic data indicate that the protonated porphyrin core forms hydrogen bonding chelates (N-H⋯X⋯H-N) to counter-anions. Weaker interactions, such as induced intramolecular C-H⋯O interactions from the porphyrin periphery are described, with distances characteristic of charge-assisted interactions. This paper offers a conceptual framework for accessing porphyrin macrocycles with designable distortion and symmetry, useful for the selective perturbation of electronic states and a design-for-application approach to solid state porphyrin materials.

Tuning the morphology of mesoscopic structures of porphyrin macrocycles functionalized by an antimicrobial peptide

The aggregation properties of two peptide–porphyrin conjugates were investigated by optical spectroscopy and microscopy imaging with nanometer resolution. Specifically, a tetraphenylporphyrin platform was functionalized by (L)-magainin, a 23-residue long antimicrobial peptide, and by a (L)-magainin analogue differing from the parent peptide by a single residue substitution, [Formula: see text] an Ala vs. Phe replacement in the position 5 of the peptide chain. Spectroscopic and microscopy results show that this single-site substitution has a small effect on the secondary structure attained by the two peptide analogues, but deeply affects the morphology of the mesoscopic structures deposited on hydrophilic mica from methanol/water solutions. In particular, only the Ala-substituted peptide-porphyrin conjugate was shown to be able to form micrometric fibrils, coating homogeneously a hydrophilic mica surface. These results pave the way for potential applications of porphyrin-peptide compounds in localized photodynamic therapy and for designing solid-state stereoselective sensors.

Carbene-Type Species in the Functionalization of Porphyrin Derivatives

Carbenes and NHCs play an important role in porphyrin chemistry and several synthetically useful transformations leading to the preparation of new porphyrin derivatives have been developed. This short review presents an overview covering the literature from 2007–2017, on the role of these transient species in the functionalization of porphyrin macrocycles.

Influence of solid matrices on spectral features of metalloporphyrins

A way of simultaneously forming in the ground electronic state a planar, as well as two distorted forms was established for a set of metalloporphyrins in solid matrices at cryogenic temperatures. Experimental data together with results of theoretical DFT calculations are combined for analysis and assignment of possible types of distorted porphyrin macrocycles conformations.