Photonic hybrid crystals constructed from in situ host–guest nanoconfinement of a light-emitting complex in metal–organic framework pores

Abstract

We report the concept underpinning the facile nanoconfinement of a bulky luminous guest molecule in the pores of a metal-organic framework (MOF) host, which yields a hybrid host ⊃ guest nanomaterial with tunable opto-electronic characteristics and enhanced photostability. Utilizing an in situ host-guest confinement strategy enabled by molecular self-assembly, we show that the highly emitting ZnQ [Zn-(bis-8-hydroxyquinoline)] guest complexes could be rapidly encapsulated within the sodalite nanocages of zeolitic imidazolate framework (ZIF-8) host crystals. The nature of optical and electronic transitions phenomena of the guest-encapsulated ZIF-8 ⊃ ZnQ has been elucidated by means of fluorescence and absorption spectroscopy measurements, and substantiated further via theoretical molecular orbital calculations revealing the plausible host-guest charge transfer mechanism involved. Evidence suggests that its photophysical properties are not only strongly determined by the host-guest co-operative bonding interactions within the environment of the confined MOF nanocage, but also can be engineered to manipulate its emission color chromaticity or to shield light-sensitive emitting guests against rapid photochemical degradation.

An updated roadmap for the integration of metal–organic frameworks with electronic devices and chemical sensors

“…Tan and co-workers demonstrated how a Znbased emitter can be encapsulated during the formation of ZIF-8, leading to significantly enhanced luminescence stability. 126 DFT moreover indicates cooperativity via a host-guest charge transfer mechanism. A second important concept is the inhibition of non-radiative decay via chromophore rotation, vibration, and torsion by anchoring such emitters into the rigid MOF backbone (Fig.…”

Framework flexibility of ZIF-8 under liquid intrusion: discovering time-dependent mechanical response and structural relaxation

“…In contrast, large guest molecules such as doxorubicin are far too large to penetrate the channels and only bind to the ZIF-8 surface, 37 whereas other bulky luminescent complexes can be entrapped within the pores of ZIF-8 using in situ nanoconfinement strategy. 38…”

Synthesis of semicrystalline nanocapsular structures obtained by Thermally Induced Phase Separation in nanoconfinement

“…The thermodynamics of macromolecules in a confined environment is extremely different from that of macroscopic systems; it has been object of numerous theoretical speculations, because of its importance in several fields including biology, medicine and nanotechnology123456789. Past investigations into phase separation of polymer solutions focused mainly on the crystallization kinetics and morphology of polymer crystals growing from bulk solutions.…”