Cyclotriphosphazenes as Scaffolds for the Synthesis of Metallomesogens

Abstract

(Amino)­cyclotriphosphazenes have been used as new scaffolds for the synthesis of silver­(I) metallomesogens. Two cyclotriphosphazenes, [N3P3(NHCy)6] (phos-1) and nongem-trans-[N3P3(NHCy)3(NMe2)3] (phos-2), were reacted with the silver complex having a pro-mesogenic ligand, [Ag­(OTf)­L] (L = CNC6H4{OC­(O)­C6H2(3,4,5-(OC10H21)3)}-4; OTf = OSO2CF3), in different molar ratios, 1:1, 1:2, or 1:3, to give two series of cationic metallophosphazenes, [N3P3(NHCy)6{AgL} n ]­(TfO) n (phos-1.n ) and nongem-trans-[N3P3(NHCy)3(NMe2)3{AgL} n ]­(TfO) n (phos-2.n ) with n = 1, 2, or 3. The chemical structure of these compounds, deduced from spectroscopic techniques, was in accordance with coordination of the silver fragments “AgL” to nitrogen atoms of the phosphazene ring, whereby their number n depends on the molar ratio used. Despite the presence of the bulky substituents on the core N atoms, cyclotriphosphazenes coordinated to three “AgL” units exhibited mesomorphism at room temperature. The mesophase was characterized as columnar hexagonal according to the optical microscopy and X-ray diffraction studies. A model based on an intermolecular association in pairs of the metallo­cyclotriphos­phazenes having three AgL units has been proposed in order to explain the mesomorphic columnar arrangement in these materials. Starting silver complex, [Ag­(OTf)­L], also exhibited a columnar hexagonal mesophase at room temperature.

Organometallic Mesogens

“…Aminocyclotriphosphazenes have been reacted with the isocyanide silver(I) complex [Ag(OTf)(CNR)] (OTf =OSO2CF3) in molar ratio 1:3, to give room temperature columnar metallomesogens 139 (R = R' = Me; R = H, R' = Cy ). 193 The same complexes in molar ratios 1:1 or 1:2 are not mesomorphic. Each silver fragment "AgCNR" is bonded to one nitrogen in the phosphazene core.…”

Gold(i) metallocyclophosphazenes with antibacterial potency and antitumor efficacy. Synergistic antibacterial action of a heterometallic gold and silver-cyclophosphazene

“…60 Indeed, we have recently reported silver-metallophosphazenes in which the silver atoms are coordinated to ring nitrogen atoms using amino-substituents at phosphorus. 62,63 Despite the potential, there are only limited examples of the use of PZ derivatives in drug delivery and metallodrugs in particular. Some antibiotic, anti-viral, antitumoral or anti-malarial drugs have been conjugated to PPZ and CPZs.…”

“…60 Indeed, we have recently reported silver-metallophosphazenes in which the silver atoms are coordinated to ring nitrogen atoms using amino-substituents at phosphorus. 62,63…”

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 first model has a calamitic structure with monosubstituted units that show the position or the upward and downward directions on the cyclotriphosphazene ring. In contrast, the second model has a star-shaped structure with polysubstituted units that organize each other parallel to the cyclotriphosphazene ring in two different levels, as the top level is darker in color and the bottom level is lighter in color. , …”