Journal of Porphyrins and Phthalocyanines

This review focuses on progress in the development of different approaches to the design of steroid ($e.g.$ estrogens, androgens, cholesterol) conjugates with coordination assemblies of metalloporphyrins, phthalocyanines and related complexes. Porphyrins and phthalocyanines have received considerable attention due to their novel composition, intriguing spectroscopic, photophysical, and redox properties, and potential application in light-harvesting and optoelectronic devices. With the development of more efficient imaging and therapeutic applications, these bio-conjugates are evaluated as multimodality agents (PET, fluorescence imaging) to monitor the mechanism of action of biologically active components in living systems and as agents for molecular recognition, oxygen atom transfer and catalysis. The tetrapyrrole components, which can be coupled via covalent and various non-covalent linkages, may exhibit strong interactions through efficient photo-induced electron and/or energy transfer processes.

The interaction of water soluble meso-tetra-(4N-oxyethylpyridyl) porphyrin (TOEPyP4) and its Cu(II)- and Co(II)-containing derivatives (CuTOEPyP4 and CoTOEPyP4) with A and B forms of DNA at low ionic strength was studied via UV-vis spectrophotometry and Circular Dichroism. It is shown that the binding constant of TOEPyP4 and CuTOEPyP4 with A–DNA is two times larger than with B–DNA, and the binding constant of CoTOEPyP4 does not depend on the form of DNA. The thermodynamical analysis based on spectral data indicates the preferable entropic character of porphyrins binding with both forms of DNA. This result shows that at low ionic strength the external groove binding mode is a preferred binding mechanism of these porphyrins with both forms of DNA.

We tested the feasibility of in-house synthesized M(Pc)(CN)${}_{\mathrm{\text{2}}}$ type axially substituted metal-phthalocyanines (M $=$ metal ion Co or Fe; Pc $=$ phthalocyanine ligand) for thin film growth via physical vapor deposition. We performed optical and infrared spectroscopy on thin films deposited in high vacuum as well as thermal desorption experiments in ultrahigh vacuum using mass spectrometry. In contradiction to the expectation of a rather strongly bound CN ligand, the results indicate molecular dissociation under the loss of CN groups at a temperature that is below the evaporation temperature of the material needed to form a film on a substrate. Therefore it was concluded that PVD is not a suitable method to grow M(Pc)(CN)${}_{\mathrm{\text{2}}}$ thin films. However, the obtained data yield valuable insight into the molecules’ stability.

The self-assembly of $\alpha$-D-glucose octafunctionalized Zn(II) phtalocyanine (ZnPc) in aqueous media has been investigated using different techniques such as UV, CD and diffusion-ordered ${}^{\mathrm{\text{1}}}$H-NMR spectroscopy (DOSY). The formation of supramolecular columnar helical aggregates with a preferred handedness due to the presence of the sugar moiety has been confirmed by these techniques. Moreover, the stability of the supramolecular polymers formed has been assessed by using pyridine as a zinc ligand, disrupting the aggregates or inducing their formation by dilution of the system.

The synthesis of three low symmetry A₂B type Mn(III)triarylcorroles with meso-aryl substituents that provide push–pull electron-donating and -withdrawing properties is reported. An analysis of the structure-property relationships for the optical and redox properties has been carried out through a comparison with the results of theoretical calculations. The results demonstrate that A₂B type Mn(III)triarylcorroles interact strongly with cell-free circulating tumor deoxyribonucleic acid (ctDNA) in solution, and that the interaction constants are enhanced when a stronger electron-donating substituent is introduced at the 10-position of the meso-triarylcorrole ligand.

Tolyporphins are unusual tetrapyrrole macrocycles produced by the filamentous cyanobacterium–microbial community HT-58-2, the only known source to date. Numerous cyanobacterial samples have been collected worldwide but most have not been screened for secondary metabolites. Identification of tolyporphins typically has entailed lipophilic extraction followed by chromatographic fractionation and spectroscopic and/or mass spectrometric analysis. For quantitation, lengthy lipophilic extraction, sample processing and HPLC separation are needed. Examination by MALDI-TOF-MS (with the matrix 1,5-diaminonaphthalene) of lipophilic crude extracts of small-scale HT-58-2 samples (2 mL) without chromatographic fractionation enabled semi-quantitation of tolyporphin A over a 41-day growth period. Screening for tolyporphin A in intact or slightly sheared and vortexed HT-58-2 samples (no lipophilic extraction), and confirmation of identity by tandem MS, were carried out by IR-MALDESI-FTMS. Tolyporphin A was identified by the molecular ion and four characteristic fragments. The molecular ion of chlorophyll $a$ also was observed. The sheared and vortexed sample contained substantial numbers of intact cells as demonstrated by regrowth of the filamentous cyanobacterium–microbial culture. The semi-quantitative and rapid qualitative methods developed herein should facilitate examination of other tolyporphin-producing organisms among the vast worldwide strains of cyanobacteria as well as investigation of the biosynthesis of tolyporphins.