Trifunctional Silyl Groups as Anchoring Units in the Preparation of Luminescent Phosphole-Silica Hybrids.

A synthetic strategy to ß-silylphospholes with three methoxy, ethoxy, chloro, hydrido, or phenyl substituents at silicon has been developed, starting from trimethoxy, triethoxy, or triphenyl silyl substituted phenyl phosphanides and 1,4-diphenyl-1,3-butadiyne. These trifunctional silylphospholes were attached to the surface of uniform spheric silica particles (15 µm) and, for comparison, to a polyhedral silsesquioxane (POSS)-trisilanol as a molecular model to explore their luminescent properties in comparison with the free phospholes. Density functional theory calculations were performed to investigate any electronic perturbation of the phosphole system by the trifunctional silyl anchoring unit. For the immobilized phospholes, cross-polarization magic-angle-spinning NMR measurements (13C, 29Si, and 31P) were carried out to explore the bonding situation to the silica surface. Thermogravimetric analysis and X-ray photoelectron spectroscopy measurements were performed to approximate the amount of phospholes covering the silica surface. Identity and purity of all novel phospholes have been established with standard techniques (multinuclear NMR, mass spectrometry, and elemental analysis) and X-ray diffraction for the POSS derivative.

Structural and Luminescence Properties of Anthracene- and Biphenyl-Based Lanthanide Bisphosphonate Ester Coordination Polymers.

Coordinative networks containing lanthanide ions attached via phosphonate ester functionalities provide remarkable luminescence properties. On the basis of ditopic phosphonic ester ligands with biphenylene and 9,10-anthracenylene bridges, a series of compounds with formal composition {[M(NO3)3]L} n or {[M(NO3)3]2(L1)3} n (L = C28H40O6P2; L1 = C26H40O6P2) with M = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y have been synthesized, structurally characterized, and the luminescence behavior was explored in the visible and NIR spectral regions, where applicable. In contrast to closely related networks based on biphenyl bisphosphonate esters from previous work, no evidence for ligand-to-metal energy transfer could be observed, despite strong near-infrared emission in some cases. Unique behavior is found for the Eu derivative with the 9,10-anthracenylene bridge, which is nonemissive, showing neither ligand- nor metal-based emission.

Coordination Polymers based on the Neutral Ditopic Ligand (C6H4PO(OCH3)2)2 Involving some f-Block Elements.

An improved synthesis using microwave heating affords (C6H4PO(OCH3)2)2 in excellent isolated yield (95 %). The ligand properties of this bisphosphonateester were explored towards hard metal centers M2+ (M = Ca, UO2) and M3+ (M = La, Ce, Sm, Eu) resulting in coordination polymers, for which the reduction of ionic size of the central metal atom resulted in lower-dimensional structural motifs as opposed to higher dimensional networks obtained for the larger ions. All coordination polymers were characterized by single-crystal X-ray diffraction, IR spectroscopy, and combustion analysis. The ligand was furthermore characterized with multinuclear NMR spectroscopy.

Facile access to efficiently luminescent Ln3+ phosphonic ester coordination polymers (Ln = Eu, Tb, Dy).

Efficiently luminescent coordination polymers containing lanthanide ions (Eu3+, Tb3+, Dy3+) can be easily obtained using a suitable bisphosphonic ester from which a heterometallic version can be elaborated showing white light emission.