On the Nature and Extent of Intermolecular Interactions between Entrapped Complexes of Ru(bpy)₃²⁺ in Zeolite Y

Abstract

A series of zeolite Y samples having different contents of entrapped Ru(bpy)3 2+ (Z−Ru(bpy)3) has been prepared. In contrast to the case in homogeneous media, in Y-zeolite the entrapped molecules cannot diffuse and the range of possible intermolecular distances between the complexes is restricted to discrete values. Because of the specific arrangement of interacting species, simplified models can be used in the study of the intermolecular interactions. The results of the present study indicate that intermolecular interactions between the entrapped complexes have a profound effect on the intensity of the electronic emission and kinetics of the excited-state depopulation. Analysis of excited-state lifetime results show that, although isolated Z−*Ru(bpy)3 molecules decay to the ground state with rates comparable to that observed in aqueous solution, the decay of the excited molecules, which have another Ru(bpy)3 2+ or *Ru(bpy)3 2+ complex entrapped in an adjacent zeolite supercage, is much more rapid. In the case of excited-state−ground-state interaction, this effect has been attributed to the nonradiative decay enhancement, and in the case of the excited-state−excited-state interaction, it has been attributed to triplet−triplet annihilation via electron transfer.

Luminescence and Energy Transfer of [Ru(bpy)3]2+, [Cr(ox)3]3-, and [Os(bpy)3]2+in Three-Dimensional Oxalato-Networks

“…Due to smaller [Ru(bpy) 3 ] 2+ concentrations the resulting migration into killer traps is less efficient, and consequently, the luminescence is less quenched. 31,32 but in the present system the effect is even more pronounced. In a simple minded picture, the tight fit of the [Ru(bpy) 3 ] 2+ complex in both the Zeolite cavities as well as is in our network structures seems to destabilize the d-d quencher state with its substantially larger metal-ligand bond length via an internal pressure.…”

Synthesis and Spectroscopic Characterization of a Zeolite-Entrapped Ru(bpy)2(dpp)2+ Complex

“…This behavior arises for some other zeolite-entrapped complexes 9-14,33 because of the contribution from small fractions (∼6%) of interacting adjacent cage pairs. 34 The lifetime for the aqueous suspension of the zeolite-entrapped Ru(bpy) 2 (dpp) 2+ complex was ∼90 ns with a second component (∼475 ns) contributing approximately 20% of the initial emission intensities. The minor component is attributable to the small fraction (less than 1%) of Z-Ru-(bpy) 3 2+ impurity and (possibly) a small contribution from interacting adjacent cage pairs.…”

Optical oxygen sensing materials based on trinuclear starburst ruthenium(II) complexes assembled in mesoporous silica

“…Mesoporous materials are able to physically encapsulate and immobilize the functional molecules into the pores, while the solvent and other small molecules or ions are allowed into the interior of the mesoporous silicas through channels. Starburst transition metal complexes which possess excellent luminescence properties because their special structure could efficiently avoid the triplet-triplet annihilation [24]. However, supporting our knowledge, there are no reports on the usage of starburst metal complexes as luminescencebased optical oxygen sensors.…”