Reaction of porphyrin-based surface-anchored metal–organic frameworks caused by prolonged illumination. Issue 46 (14th November 2018)

• Record Type: Journal Article
• Authors: Adams, Michael; Baroni, Nicolò; Oldenburg, Michael; Kraffert, Felix; Behrends, Jan; MacQueen, Rowan W.; Haldar, Ritesh; Busko, Dmitry; Turshatov, Andrey; Emandi, Ganapathi; Senge, Mathias O.; Wöll, Christof; Lips, Klaus; Richards, Bryce S.; Howard, Ian A.
• Is Part Of: Physical chemistry chemical physics. Volume 20:Issue 46(2018)
• Page Start: 29142
• Page End: 29151
• Publication Date: 2018-11-14
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c8cp05254a
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Upon prolonged illumination photoproducts are created in porphyrin-based metal–organic frameworks that limit the triplet exciton lifetime by charge-transfer quenching. Abstract : Crystalline surface-anchored metal–organic framework (SURMOF) thin films made from porphyrin-based organic linkers have recently been used in both photon upconversion and photovoltaic applications. While these studies showed promising results, the question of photostability in this organic–inorganic hybrid material has to be investigated before applications can be considered. Here, we combine steady-state photoluminescence, transient absorption, and time-resolved electron paramagnetic resonance spectroscopy to examine the effects of prolonged illumination on a palladium-porphyrin based SURMOF thin film. We find that phototreatment leads to a change in the material's photoresponse caused by the creation of stable products of photodecomposition – likely chlorin – inside the SURMOF structure. When the mobile triplet excitons encounter such a defect site, a short-lived (80 ns) cation–anion radical pair can be formed by electron transfer, wherein the charges are localized at a porphyrin and the photoproduct site, respectively.