Zinc, Cadmium, and Mercury Complexes of a Pyridyloxy-Substituted Cyclotriphosphazene: Syntheses, Structures, and Fluxional Behavior

Progress in the Field of Cyclophosphazenes: Preparation, Properties, and Applications

This review article provides a comprehensive overview of recent advancements in the realm of cyclophosphazenes, encompassing their preparation methodologies, distinctive properties, and diverse applications. The synthesis approaches are explored, highlighting advancements in the preparation of these cyclic compounds. The discussion extends to the distinctive properties exhibited by cyclophosphazenes, including thermal stability characteristics, and other relevant features. Furthermore, we examine the broad spectrum of applications for cyclophosphazenes in various fields, such as coatings, adhesives, composites, extractants, metal complexes, organometallic chemistry, medicine, and inorganic chemistry. This review aims to offer insights into the evolving landscape of cyclophosphazenes and their ever-expanding roles in contemporary scientific and technological arenas. Future possibilities are emphasized, and significant research data shortages are identified.

Study of interaction of metal ions with methylthymol blue by chemometrics and quantum chemical calculations

In this study, we determine the acidity constants of methylthymol blue (MTB) and association constants of its complexes with the ZnII, CuII, and FeII metal ions (MIs), through theoretical and experimental means. The complexes were characterized using UV-Visible absorption spectroscopy combined with soft/hard chemometrics methods and quantum chemical calculations. Quantum chemical calculations revealed that electronic transitions in the UV-Visible spectra of MTB have mixed n → π* and π → π* characters. The results of molar ratio and multivariate curve resolution alternating least squares (MCR-ALS) revealed the formation of successive 1:2 and 1:1 complexes (MI:MTB) for the ZnII and CuII systems. However, the formation of successive 1:1 and 2:1 complexes are suggested for FeII by the molar ratio and MCR-ALS. The majority of transitions observed in the UV-Visible spectra of the Zn(MTB) and Cu(MTB) complexes have ligand-to-ligand charge transfer (LLCT) characters. However, the transitions in the UV-Visible spectrum of the Fe(MTB) complex have LLCT and metal-to-ligand charge transfer (MLCT) characters. For the Fe2(MTB) complex, the lowest energy transition of has an LLCT character. However, its higher energy transitions are a mixture of LLCT, MLCT, and metal-to-metal charge transfer (MMCT) characters. The correlation between experimental and computed wavelengths revealed that the 1:1 complexes of ZnII and CuII prefer square pyramidal geometries. However, the FeII complexes always show octahedral geometry.

Nucleophilic substitution reactions of monofunctional nucleophilic reagents with cyclotriphosphazenes containing 2,2-dioxybiphenyl units

The nucleophilic substitution reactions of mono- and bis-spiro-2,2' -dioxybiphenyl cyclotriphosphazenes (3 and 4) with cyclopropanemethylamine (5) and aniline (6) were performed in the presence of trimethylamine in THF. Five novel cyclopropanemethylamino- and anilino-substituted spiro-2,2' -dioxybiphenyl cyclotriphosphazene derivatives (7-11) were obtained from these reactions. The molecular structures of the new cyclotriphosphazene derivatives (7-11) were characterized by elemental analysis, MALDI-TOF MS, FT-IR, and NMR ( ³¹ P and ¹ H) spectroscopies. The structure of the spiro-(2,2' -dioxybiphenyl)-bis-(anilino)-cyclotriphosphazene (11) was also determined by single-crystal X-ray crystallography.

New hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugates as highly selective and sensitive fluorescent chemosensor for Co2+ ions

In the study, the new hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugates (HBCP 1 and 2) have been successfully synthesized and characterized by using general spectroscopic techniques such as ¹H, ¹³C and ³¹P NMR spectroscopies. The photophysical and metal sensing properties in THF solutions of dendrimeric cyclotriphosphazene conjugates (HBCP 1 and 2) were investigated by UV-Vis and fluorescence spectroscopies in dilute tetrahydrofuran solutions. These dendrimers showed strong absorption bands 501 and 641nm at low concentration with high molar extinction coefficients. In addition, the stoichiometry of the complex between the conjugate (HBCP 2) and Co²⁺ ions were determined by a Job's plot obtained from fluorescence titrations. The metal sensing data showed that the hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugate (HBCP 2) is a candidate for fluorescent chemosensor for Co²⁺ ions due to showing high selectivity with a low limit of detection.

Fluxional motion in a dinuclear copper(i) complex with a propeller-type ligand: metal hopping on both sides

Fluxional motion of a dicopper(i) complex of hexa(2-pyridyl)benzene that accompanies metal hopping processes and ring rotation was studied.

Silver(I) coordination polymers assembled from flexible cyclotriphosphazene ligand: structures, topologies and investigation of the counteranion effects

The reactions of a flexible ligand hexakis(3-pyridyloxy)cyclotriphosphazene (HPCP) with a variety of silver(I) salts (AgX;X= NO3−, PF6−, ClO4−, CH3PhSO3−, BF4−and CF3SO3−) afforded six silver(I) coordination polymers, namely {[Ag2(HPCP)]·(NO3)2·H2O}n(1), {[Ag2(HPCP)(CH3CN)]·(PF6)2}n(2), {[Ag2(HPCP)(CH3CN)]·(ClO4)2}n(3), [Ag3(HPCP)(CH3PhSO3)3]n(4), [Ag2(HPCP)(CH3CN)(BF4)2]n(5) and {[Ag(HPCP)]·(CF3SO3)}n(6). All of the isolated crystalline compounds were structurally determined by X-ray crystallography. Changing the counteranions in the reactions, which were conducted under similar conditions ofM/Lratio (1:1), temperature and solvent, resulted in structures with different types of topologies. In complexes (1)–(6), the ligand HPCP shows different coordination modes with AgIions giving two-dimensional layered structures and three-dimensional frameworks with different topologies. Complex (1) displays a new three-dimensional framework adopting a (3,3,6)-connected 3-nodal net with point symbol {4.62}2{42.610.83}. Complexes (2) and (3) are isomorphous and have a two-dimensional layered structure showing the same 3,6L60 topology with point symbol {4.26}2{48.66.8}. Complex (4) is a two-dimensional structure incorporating short Ag...Ag argentophilic interactions and has a uninodal 4-connectedsql/Shubnikov tetragonal plane net with {44.62} topology. Complex (5) exhibits a novel three-dimensional framework and more suprisingly contains twofold interpenetrated honeycomb-like networks, in which the single net has a trinodal (2,3,5)-connected 3-nodal net with point symbol {63.86.12}{63}{8}. Complex (6) crystallizes in a trigonal crystal system with the space group R\bar 3 and possesses a three-dimensional polymeric structure showing a binodal (4,6)-connectedfshnet with the point symbol (43.63)2.(46.66.83). The effect of the counteranions on the formation of coordination polymers is discussed in this study.

BODIPY decorated dendrimeric cyclotriphosphazene photosensitizers: synthesis and efficient singlet oxygen generators

BODIPY decorated dendrimeric cyclotriphosphazenes were synthesized. The singlet oxygen generation capabilities of them were evaluated. They are proposed as potential photosensitizers that can be used as efficient singlet oxygen generators.

Molecular, 1D and 2D assemblies from hexakis(3-pyridyloxy)cyclophosphazene containing 20-membered metallamacrocyclic motifs

The coordination behaviour of hexakis(3-pyridyloxy)cyclophosphazene (L) towards divalent metal ions is described. The reaction of L with hydrated metal nitrates afforded [{N3P3(O-C5H4N-3)6}2{Zn(H2O)3(NO3)}2{Zn(H2O)2(NO3)}2]n[NO3]2n·4nH2O·nCH3OH (1), [{N3P3(O-C5H4N-3)6}2{Zn(H2O)3(NO3)}2{Cu(NO3)}2]n[NO3]2n·4nH2O·nCH3CN (2), [{N3P3(O-C5H4N-3)6}2{(NO3)Cd-(μ-(NO3)-Cd(NO3)2(μ-(NO3)Cd(NO3)}]n·2nCH3OH·3nH2O (3), and [{N3P3(O-C5H4N-3)6}2{Cd(H2O)3(NO3)}2][NO3]2·9H2O (4). 1 and 2 are one-dimensional coordination polymers while 3 is a two-dimensional coordination polymer. On the other hand 4 is a molecular metallamacrocycle. A common feature of 1-4 is the presence of a 20-membered dimetallamacrocyclic motif constructed through the involvement of a pair of cyclophosphazene ligands through their geminal pyridyloxy substituents. The P-N bond distances in L and its metal complexes 1-4 are nearly the same indicating the flexible nature of the coordination pyridyloxy arms present on the cyclophosphazene scaffold.