Barbituric acids as a useful tool for the construction of coordination and supramolecular compounds

Mechanisms of Inorganic Reactions. A Study of Metal Complexes in Solution.

Chemical modification at the periphery with nitrogen or chalcogens is a highly promising strategy to diversify the optical, electrochemical, magnetic, and coordination properties of the porphyrin family. Indeed, various kinds of phthalocyanines and related benzo-annelated azaporphyrinoids have been synthesized, and their fundamental properties have been extensively investigated. However, the synthesis of heteroatom-containing porphyrins in which the peripheral methine groups are partially replaced with nitrogen or chalcogens remains a considerable challenge. In this review, we will focus mainly on recent advances in the synthesis of aza-, oxa-, and thiaorphyrins and related compounds, including historically important examples.

Synthesis of Aza-, Oxa-, and Thiaporphyrins and Related Compounds.

Tetraphenylporphyrin (H2TPP) and zinc tetraphenylporphyrin (ZnTPP) are widely used benchmark molecules in diverse photochemical studies given facile synthetic access, rich visible-region spectra, and broad structural analogy to chlorophylls. Yet the literature values for each key photophysical parameter – the molar absorption coefficient (e), fluorescence quantum yield (Φf), and also singlet excited-state lifetime (τS) – vary over an astonishing range. Here, a comprehensive literature review (∼1940–September 2020) encompassing 871 publications is reported for these essential parameters. Each parameter is determined by measurement with distinct instrumentation and suffers idiosyncratic sources of error. The best values for H2TPP are e = 460,000 cm−1·M−1, Φf = 0.090, and τS = 12.8 ns in Ar- purged toluene (Φf = 0.070, τS = 9.9 ns in toluene in air); the best values for ZnTPP are e = 560,000 cm−1·M−1, Φf = 0.030, and τS = 2.1 ns in Ar-purged toluene (Φf = 0.029, τS = 2.0 ns in toluene in air). The choice of values for such parameters has far-reaching consequences in photochemistry ranging from fluorescence (or Forster) resonance energy transfer (FRET) processes to assessments of molecular brightness.

Comprehensive review of photophysical parameters (ε, Φf, τs) of tetraphenylporphyrin (H2TPP) and zinc tetraphenylporphyrin (ZnTPP) – Critical benchmark molecules in photochemistry and photosynthesis

Metalloporphyrins which form the core of many bioenzymes and natural light harvesting or electron transport systems, exhibit a variety of selective functional properties depending on the state and surroundings with which they exist in biological systems. The specificity and ease with which they function in each of their bio-functions appear to be largely governed by the nature and disposition of the protein globule around the porphyrin reaction center. Synthetic porphyrin frameworks confined within or around a pre-organized molecular entity like the protein network in natural systems have attracted considerable attraction, especially in the field of biomimetic reactions. At the same time a large number of macrocyclic oligomers such as calixarenes, resorcinarenes, spherands, cyclodextrins and crown ethers have been investigated in detail as efficient molecular receptors. These molecular receptors are synthetic host molecules with enclosed interiors, which are designed three dimensionally to ensure strong and precise molecular encapsulation/recognition. Due to their complex structures, enclosed guest molecules reside in an environment isolated from the outside and as a consequence, physical properties and chemical reactions specific to that environment in these guest species can be identified. The facile incorporation of such molecular receptors into the highly photoactive and catalytically efficient porphyrin framework allows for convenient design of useful molecular systems with unique structural and functional properties. Such systems have provided over the years attractive model systems for the study of various biological and chemical processes, and the design of new materials and molecular devices. This review focuses on the recent developments in the synthesis of porphyrin assemblies associated with cyclodextrins, calixarenes and resorcinarenes and their potential applications in the fields of molecular encapsulation/recognition, and chemical catalysis.

https://www.mdpi.com/1420-3049/17/10/11763/pdf

Molecular Assemblies of Porphyrins and Macrocyclic Receptors: Recent Developments in Their Synthesis and Applications

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Complexation Properties of Octa(4-bromophenyl)tetraazaporphyrin and Its Magnesium(II) Complex with Salts of d-Metals in DMF

Interaction of 5,10,15,20-tetraphenylporphyrin, 2-bromo-5,10,15,20-tetraphenylporphyrin, and 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin with manganese(II) chloride in dimethylformamide has been studied by means of spectrophotometry. The corresponding chloride acido complexes of manganese(III) has been so prepared and identified. The complexes could be reduced into manganese(II) tetraphenylporphyrinates in the presence of potassium hydroxide in dimethylformamide.

Preparation and spectral properties of β-bromo-substituted Mn(III) tetraphenylporphyrinates

The problem of the use of a natural pigment, chlorophyll, as ecologically pure dye for textile fibers is discussed. The physicochemical principles of the synthesis of metalocontaining compounds based on chlorophyll derivatives used for development of chlorophyll and porphyrin dyes of new generation, which are more ecologically safe than the arene-based dyes.

Synthesis and use of ecologically pure metal-containing dyes based on chlorophyll derivatives

The reaction of (octaphenyltetraazaporphyrinato)magnesium(II) with manganese(II) chloride in dimethylformamide gave (chloro)(octaphenyltetraazaporphyrinato)manganese(III) Reactions of the latter with nitrogen-containing bases were studied The kinetic parameters of the transmetalation of (octaphenyltetraazaporphyrinato) magnesium(II) with MnCl2 in dimethylformamide at 323, 333, and 343 K were determined, and a probable reaction mechanism was proposed

Transmetalation of (octaphenyltetraazaporphyrinato)magnesium(II) with manganese(II) chloride in dimethylformamide

Metal exchange between cadmium protoporphyrin CdPP and zinc and cobalt chlorides in dimethyl sulfoxide (DMSO) and acetonitrile (AN) was studied by spectrophotometry. Comparative analysis of the data on metal exchange between CdPP and ZnCl2 in DMSO and between CdPP and CoCl2 in AN was performed. The possible exchange mechanisms were considered. The results were compared with the data on cadmium mesoporphyrin exchange with zinc and cobalt.

S. V. Zvezdina

Papers

Complexation Properties of Octa(4-bromophenyl)tetraazaporphyrin and Its Magnesium(II) Complex with Salts of d-Metals in DMF

Preparation and spectral properties of β-bromo-substituted Mn(III) tetraphenylporphyrinates

Synthesis and use of ecologically pure metal-containing dyes based on chlorophyll derivatives

Transmetalation of (octaphenyltetraazaporphyrinato)magnesium(II) with manganese(II) chloride in dimethylformamide

Metal exchange reactions between cadmium protoporphyrin and cobalt and zinc chlorides in acetonitrile and dimethyl sulfoxide