Chiral configurations in cyclophosphazene chemistry

Synchronous modification of ZIF-67 with cyclomatrix polyphosphazene coating for efficient flame retardancy and mechanical reinforcement of epoxy resin

Cyclomatrix polyphosphazenes have attracted widespread attention in the field of polymer flame retardancy. Nevertheless, the optimal manifestation of their distinctive structural attributes and flame-retardant properties necessitates a judicious selection of condensation monomers and synergistic templates during the fabrication of polyphosphazene flame retardants. In our previous studies, it was discovered that when ZIF-67 is functionalized with polyphosphazene, the by-product HCl from phosphazene polycondensation causes etching on ZIF-67. Based on this "synchronous etching" effect, a series of hybrid materials comprising cyclomatrix polyphosphazene and ZIF-67, denoted as ZIF-67@PDS (PDS, poly-(cyclotriphosphazene-co-4,4'-diaminodiphenyl sulfone)), ZIF-67@PBS (PBS, poly-(cyclotriphosphazene-co-Bisphenol A)), and ZIF-67@PZS (PZS, poly-(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)), was synthesized utilizing DDS (4,4'-diaminodiphenyl sulfone), BPA (Bisphenol A), and BPS (4,4'-sulfonyldiphenol) monomers as precursors, respectively. Upon the incorporation of 2.0 wt.% of ZIF-67@PDS, ZIF-67@PBS, and ZIF-67@PZS, the flame retardant and mechanical characteristics of EP composites exhibited marked enhancement. The unique structural characteristics of hybrid and the synergistic effects of Co-P-N contribute to the improvement of comprehensive properties. Compared with pure EP, EP/ZIF-67@PZS has the best enhancement effect, and its pHRR, THR, and TSP decreased by 34.0%, 30.0%, and 40.5%, respectively. In terms of mechanical strength, ZIF-67@PZS also increases the flexural strength of EP by 37.42%. Relying on the "synchronous etching" effect, this study explores and verifies the effective combination of ZIF-67 and different types of polyphosphazenes, and obtains a series of ZIF-67-derived cyclomatrix polyphosphazene hybrids with different morphologies and properties in one step. It provides a new idea and strategy for the simultaneous modification of polyphosphazene materials and the preparation of multifunctional flame retardants in the future.

Construction of Indium(III)-Organic Framework Based on a Flexible Cyclotriphosphazene-Derived Hexacarboxylate as a Reusable Green Catalyst for the Synthesis of Bioactive Aza-Heterocycles

The constant demand for eco-friendly methods of synthesizing complex organic compounds inspired researchers to design and develop modern, highly efficient heterogeneous catalytic systems. Herein, In-HCPCP metal-organic framework (SRMIST-1), a heterogeneous Lewis acid catalyst containing less toxic indium and eco-friendly robust cyclotriphosphazene and exhibiting notable chemical and thermal stability, durable catalytic activity, and exceptional reusability was produced through the reaction between indium(III) nitrate hydrate and hexakis(4-carboxylatophenoxy)-cyclotriphosphazene. In the SRMIST-1 structure, secondary building units {InO7} are assembled by a connection of η2- and η1-carboxylic oxo atoms from different HCPCP ligands, forming a three-dimensional network. The occurrence of regularly distributed In(III) sites in SRMIST-1 confers superior reactivity on the catalyst toward the synthesis of 2,3-dihydroquinazolin-4(1H)-ones and 3,4-dihydro-2H-1,2,4-benzothiadiazine-1,1-dioxides by the cyclization reaction of 2-aminobenzamides and 2-aminobenzenesulphonamides with aldehydes under optimized reaction conditions, respectively. The notable features of this method include broad functional group compatibility, low catalyst loading (1-5 mol %), mild reaction conditions, easy workup procedures, good to excellent reaction yields, ethanol as a green solvent, reusability of the catalyst (five cycles), and economic attractiveness, which is mainly due to sustainability of SRMIST-1 as a reusable green catalyst. Our findings demonstrate that the highly reactive and reusable green catalyst finds widespread applications in medicinal chemistry.

Cyclo- and Polyphosphazenes for Biomedical Applications

Cyclic and polyphosphazenes are extremely interesting and versatile substrates characterized by the presence of -P=N- repeating units. The chlorine atoms on the P atoms in the starting materials can be easily substituted with a variety of organic substituents, thus giving rise to a huge number of new materials for industrial applications. Their properties can be designed considering the number of repetitive units and the nature of the substituent groups, opening up to a number of peculiar properties, including the ability to give rise to supramolecular arrangements. We focused our attention on the extensive scientific literature concerning their biomedical applications: as antimicrobial agents in drug delivery, as immunoadjuvants in tissue engineering, in innovative anticancer therapies, and treatments for cardiovascular diseases. The promising perspectives for their biomedical use rise from the opportunity to combine the benefits of the inorganic backbone and the wide variety of organic side groups that can lead to the formation of nanoparticles, polymersomes, or scaffolds for cell proliferation. In this review, some aspects of the preparation of phosphazene-based systems and their characterization, together with some of the most relevant chemical strategies to obtain biomaterials, have been described.

Phosphazene Cyclomatrix Network-Based Polymer: Chemistry, Synthesis, and Applications

Polyphosphazenes are an inorganic molecular hybrid family with multifunctional properties due to their wide range of organic substitutes. This review intends to propose the basics of the synthetic chemistry of polyphosphazene, describing for researchers outside the field the basic knowledge required to design and prepare polyphosphazenes with desired properties. A special emphasis is placed on recent advances in chemical synthesis, which allow not only the synthesis of polyphosphazenes with controlled molecular weights and polydispersities but also the synthesis of novel branched designs and block copolymers. We also investigated the synthesis of polyphosphazenes using various functional materials. This review aims to assist researchers in synthesizing their specific polyphosphazene material with unique property combinations, with the hope of stimulating further research and even more innovative applications for these highly interesting multifaceted materials.

Phosphorus-Nitrogen Compounds. Part 64. Comparative Reactions of Spiro and Ansa(N/O) Cyclotetraphosphazenes with Bulky (4-Fluorobenzyl) N/N and N/O Donor Type Bidentate Reagents: Structure, Stereogenic Properties and Cytotoxic activity Studies

The reaction of octachlorocyclotetraphosphazene, N4P4Cl8 (1) (OCCP, tetramer) with an equimolar amount of sodium 3-(N-ferrocenylmethylamino)-1-propanoxide (L1) resulted in the formations of ferrocenyl-spiro-(2) and ferrocenyl-2-cis-4-dichloro-ansa-(3) cyclotetraphosphazenes. Both of the starting compounds...

Phosphorus-Nitrogen Compounds. Part 65. Novel diansa-spiro-cyclotetraphosphazenes: synthesis, characterization, bioactivity and electrochemical properties, fabrication of dye-sensitized solar cell studies

In this investigation, the substitution reaction of octachlorocyclotetraphosphazene, N4P4Cl8 (tetramer, OCCP, 1) with sodium 3-(N-ferrocenylmethylamino)-1-propanoxide (L1) was found to yield the compounds, 2,4-ansa- (2) and spiro- (2) cyclotetraphosphazene derivatives. The...

Phosphorus–nitrogen compounds: part 63. Mono- and bis-vanillinatobisferrocenyldispiro(N/N)cyclotriphosphazenes and their macrocyclic Schiff-bases: synthesis, structural characterization and isomerism

Mono/bis-vanillinato ferrocenyldispirocyclotriphosphazenes and Schiff-bases were obtained. Structures of the compounds were determined using spectroscopic methods. Absolute configurations of three compounds were defined by X-ray crystallography.

Recent advances in the supramolecular assembly of cyclophosphazene derivatives

There is still room for improvement in supramolecular systems based on cyclophosphazene derivatives and their potential applications.

Unexpected formation of ansa isomers enabled by phosphazene ring flexibility in the reactions of cyclotetraphosphazene with 1,2-ethanediol

In this work, the nucleophilic substitution reactions of the cyclotetraphosphazene, tetramer, (1) (N4P4Cl8) with the disodium salt of 1,2-ethanediol in THF solution at different mole ratios were demonstrated. Surprisingly, one double bridged (2) and three ansa derivatives [bis (3), tris (4) and tetrakis (5)] were formed demonstrating two competing pathways in these reactions. The new type cyclotetraphosphazene compounds (2-5) consisting of multiple rings were characterized by elemental analysis, mass spectrometry, 1H and 31P NMR spectroscopy and X-Ray crystallography. Although 1,2-ethanediol, a short chain diol, can only produce spiro type products with cyclotriphosphazene, (N3P3Cl6), it was able to give ansa type products with cyclotetraphosphazene which suggests the role of the ring flexibility of 1. Crystallographic evidence shows the distortion of the cyclotetraphosphazene ring.

Phosphorus–nitrogen compounds. Part 54. syntheses of chiral amino-4-fluorobenzyl-spiro(N/O)cyclotriphosphazenes: structural and stereogenic properties

Syntheses, spectral and crystallographic characterizations and stereogenic properties by ³¹P NMR spectra recorded with the addition of CSA, CD spectra and chiral HPLC of amino-4-fluorobenzylspiro(N/O)cyclotriphosphazenes were examined.

Phosphazene based star-branched polymeric cathode materials via inverse vulcanization of sulfur for lithium–sulfur batteries

Novel insoluble star-shaped hexa-branched polymeric materials based on cyclotriphosphazene core are prepared by the inverse vulcanization of sulfur with hexakis(styreneoxy)cyclotriphosphazene and tested as cathode for lithium–sulfur (Li–S) batteries.

Syntheses, spectral and chiral properties and DNA interactions of multi-heterocyclic di- and trinuclear boron complexes

Stereoisomers of Salen-boron complexes with two equivalent stereogenic B-centers giving rise to diastereoisomers were assigned by CD and NMR spectra.

Phosphorus–nitrogen compounds. Part 42. The comparative syntheses of 2-cis-4-ansa(N/O) and spiro(N/O) cyclotetraphosphazene derivatives: spectroscopic and crystallographic characterization, antituberculosis and cytotoxic activity studies

Syntheses, structural properties and biological activities of ferrocenyl ansa- and spiro-cyclotetraphosphazenes were investigated.

Syntheses, spectroscopic and crystallographic characterizations of cis- and trans-dispirocyclic ferrocenylphosphazenes: molecular dockings, cytotoxic and antimicrobial activities

The crystallographic and molecular docking investigations and the determinations of the cytotoxic activities of the dispirocyclic ferrocenylphosphazenes were performed.