Electrochemical, Spectroelectrochemical, and Structural Studies of Mono- and Diphosphorylated Zinc Porphyrins and Their Self-Assemblies

Abstract

Three series of porphyrins containing a Zn(II) central metal ion and zero, one or two phosphoryl groups at the mesopositions of the macrocycle were characterized as to their electrochemical, spectroscopic and structural properties in non-aqueous media. The investigated compounds are represented as 5,15-bis(4'-R-phenyl)porphyrinatozinc, 10-(diethoxyphosphoryl)-5,15bis(4'-R-phenyl)porphyrinatozinc and 5,15-bis(diethoxyphosphoryl)-10,20-bis(4'-R-phenyl)porphyrinatozinc, where R = OMe, Me, H or CN. Linear-free energy relationships are observed between the measured redox potentials at room temperature and the electronic nature of the substituents at the 5 and 15 meso-phenyl groups of the macrocycle. The mono-and bis-phosphoryl derivatives with two p-CNPh substituents provide electrochemical evidence for aggregation at low temperature, a greater degree of aggregation being observed in the case of 5,15-bis(diethoxyphosphoryl)-10,20-bis(4'-CN-phenyl)porphyrinatozinc(II). This compound was characterized in further detail by variable temperature 1 H and 31 P{ 1 H} NMR spectroscopy in solution combined with single crystal X-ray analysis in the solid state. The data obtained from these measurements indicating that this porphyrin has a dimeric structure in CDCl 3 at 223-323 K but forms a 2D polymeric network when it is crystalized from a CHCl 3 /MeOH mixture.

Recent progress in organometallic porphyrin‐based molecular materials for optical sensing, light conversion, and magnetic cooling

“…In the moment, different authors use all possible principles for the formation of porphyrin-fullerene dyads, namely, covalent and donor-acceptor bonding, coprecipitation, complex formation with partial and complete electron transfer, π-π stacking, and the formation of radical salts. [131][132][133][134][135] Molecular complexation studied on available ZnP or MPc [25,39,[136][137][138][139][140][141][142][143][144][145][146][147][148] shows higher efficiency compared with covalent C-C bonding in the vast majority of works in photovoltaics. It is distinctly shown in the work [149] that the azulenocyanine moiety in the covalent Zn-azulenocyanine-C 60 dyad shuts down the electron transfer, whereas axial bonding in this system evokes good electronic coupling between the excited state electron donor and the ground state electron acceptor.…”

“…Metalloporphyrins (MPs) are studied and applied ascatalysts, [4][5][6][7][8] , chemical probes for ions, ion pairs, volatile organic compounds (VOCs), nitroaromatic compounds, gases, reactive oxygen species, [9] optical chemosensors, [10][11][12][13][14][15][16] semiconductors, [17][18][19][20][21] functional dyes for organic solar cells, [19,[22][23][24] and photodynamic therapy. [19,25,26] Porphyrin/phthalocyanine derivatives of both the paramagnetic ions of 3d elements and rare earth element (REE) were widely studied as single-molecule magnets (SMMs) at the temperatures close to 0 K. [27][28][29][30][31][32] The derivatives displaying the Curie-Weiss behavior above the Curie temperature were studied as materials with a magnetocaloric effect (MCE) at the temperature close to room that is far from the temperature of the magnetic phase transition. [33][34][35] There are two different ways to develop the chemistry of the porphyrin-based materials, namely, studying/ applying these in the form of molecular materials [36][37][38][39] and designing nanoscale/crystalline samples or composites.…”

“…[40][41][42][43][44][45] Though the second way demonstrates endless possibilities, the field of the first-way subjects is limited by metal derivatives of tetrapyrroles whose single molecule exhibits property of a molecular material. From the cited articles, it is clear that most results are connected with two charged zinc [25,26,39,42] or cobalt [43] porphyrin/ phthlocyanines. Reason for their study, as it would seem, "lies on the surface."…”

“…[ 40–45 ] Though the second way demonstrates endless possibilities, the field of the first‐way subjects is limited by metal derivatives of tetrapyrroles whose single molecule exhibits property of a molecular material. From the cited articles, it is clear that most results are connected with two charged zinc [ 25,26,39,42 ] or cobalt [ 43 ] porphyrin/phthlocyanines. Reason for their study, as it would seem, “lies on the surface.” They are characterized by both the available synthesis from preprepared porphyrin or a pyrrole‐based precursor and vacant axial positions suitable for the following design of nanostructures/composites.…”

Reactive Dissolution of Organic Nanocrystals at Controlled pH

“…Among many organic materials, porphyrin molecules represent relevant building‐blocks for functional material whose optical/electronic properties can be modulated electrochemically or by the proper control of pH and solvent . Nowadays, controlling the morphology of advanced organic materials is a key task for their applications in different fields, ranging from the fabrication of organic electronic devices, sensors, as well as applications to the biomedical field .…”