Photon Upconversion in a Glowing Metal–Organic Framework

Abstract

The interaction of low-energy light with matter that leads to the production of high-energy light is known as photon upconversion. This phenomenon is of importance because of its potential applications in optoelectronics, energy harvesting, and the biomedical arena. Herein, we report a pillared-paddlewheel metal–organic framework (MOF), constructed from a tetrakis­(4-carboxyphenyl)­porphyrin sensitizer and a dipyridyl thiazolothiazole annihilator, designed for efficient triplet–triplet annihilation upconversion (TTA-UC). Single-crystal X-ray diffraction studies reveal that the Zn-metalated sensitizers are coordinated to Zn2 nodes in a paddlewheel fashion, forming 2D sheets, to which are linked annihilators, such that each sensitizer is connected to five of them. The precise arrangements of sensitizers with respect to annihilators, and the high annihilator-to-sensitizer ratio, facilitate Dexter energy transfer. This level of organization in an extended structure leads to a high TTA-UC efficiency of 1.95% (theoretical maximum = 50%) at an excitation power density of 25 mW cm–2.

van der Waals solid solution crystals for highly efficient in-air photon upconversion under subsolar irradiance

“…Although the number of reports is limited, some studies used nonkinetic approaches. 13,[42][43][44][45] For example, Oldenburg et al 42 fabricated sensitizer annihilator heterojunctions of thin metal organic framework (MOF) layers and reported UC < 0.1% and an excitation threshold intensity (Ith) of ca. 1 mW cm 2 .…”

“…Ogawa et al 43 reported an aggregation-free dispersion of an anionic sensitizer in the crystal of an ionic annihilator utilizing ionic interactions between the chromophores ( UC = 3% and Ith = 49 mW cm 2 in Ar); in which photographs of the crystals, photostability data, and information on whether or not the crystals included the solvent methanol were not presented. Recently, Roy et al 45 reported MOF crystals with UC = 1.95% and Ith = 5.1 mW cm 2 . However, these values were, as in other MOF-based reports, 13,44 for a liquid suspension and no photostability data was shown; whereas ref.…”

Straightforward synthesis of thiazolo[5,4-c]isoquinolines from dithiooxamide and 2-halobenzaldehydes

“…The reaction between dithiooxamide and aromatic aldehydes is a well-known and extensively used route to thiazolo[5,4- d ]thiazoles (TzTz). 18 TzTz, due to the rigidity and stability of their backbone, together with their outstanding charge carrier mobility, are attractive compounds for application in the electronic and optoelectronic fields 19–29 and in other relevant areas, namely as fluorescent probes and sensors. 30–34 However, we found that this classic reaction can be used to prepare thiazolo[5,4- c ]isoquinolines starting from simple commercially available reagents (dithiooxamide and benzaldehyde derivatives).…”

Self-Assembly-Directed Exciton Diffusion in Solution-Processable Metalloporphyrin Thin Films

“…Porphyrins are tetrapyrrole-based aromatic macrocycles containing fully conjugated 18 π-electrons. Porphyrins have been used as linkers in metal and covalent organic frameworks and for a wide variety of applications, such as photovoltaics, photocatalysis, and energy storage [ 12 , 13 , 14 ]. Porphyrins have also been explored for biomedical applications, photodynamic therapy, sensing and spintronics [ 15 , 16 , 17 , 18 ].…”