Transformational Modulation of Fluorescence to Room Temperature Phosphorescence in Metal-Organic Frameworks with Flexible C-S-C Bonds

Huili Sun; Qiangsheng Zhang; Zhonghao Wang; Yanting Huang; Mei Pan

doi:10.1021/acsami.4c00400

Transformational Modulation of Fluorescence to Room Temperature Phosphorescence in Metal-Organic Frameworks with Flexible C-S-C Bonds

ACS Appl Mater Interfaces. 2024 Mar 6;16(9):11730-11739. doi: 10.1021/acsami.4c00400. Epub 2024 Feb 26.

Authors

Huili Sun¹, Qiangsheng Zhang¹, Zhonghao Wang¹, Yanting Huang¹, Mei Pan¹

Affiliation

¹ MOE Laboratory of Bioinorganic and Synthetic Chemistry, Lehn Institute of Functional Materials, IGCME, GBRCE for Functional Molecular Engineering, School of Chemistry, Sun Yat-Sen University, Guangzhou 510006, China.

PMID: 38407090
DOI: 10.1021/acsami.4c00400

Abstract

Photoluminescent metal-organic frameworks (MOFs) have been a subject of considerable interest for many years. However, the regulation of excited states of MOFs at the single crystal level remains restricted due to a lack of control methods. The singlet-triplet emissive property can be significantly influenced by crystal conformational distortions. This review introduces an intelligent responsive MOF material, denoted as LIFM-SHL-3a, characterized by flexible C-S-C bonds. LIFM-SHL-3a integrates elastic structural dynamics with fluorescence and room temperature phosphorescence (RTP) modulation under heating conditions. The deformable carbon-sulfur bond essentially propels the distortion of molecular conformation and alters the stacking mode, as illustrated by single-crystal-to-single-crystal transformation detection. The deformation of flexible C-S-C bonds leads to different noncovalent interactions in the crystal system, thereby achieving modulation of the fluorescence (F) and RTP bands. In the final state structure, the ratio of fluorescence is 66.7%, and the ratio of RTP is 32.6%. This stands as a successful demonstration of modulating F/RTP within the dynamic MOF, unlocking potential applications in optical sensing and beyond. Especially, a PL thermometer with a relative sensitivity of 0.096-0.104%·K^-1 in the range of 300-380 K and a H₂S probe with a remarkably low LOD of 125.80 nM can be obtained using this responsive MOF material of LIFM-SHL-3a.

Keywords: flexible C−S−C bond; metal−organic frameworks (MOFs); optical sensing; room temperature phosphorescence (RTP); single-crystal-to-single-crystal (SCSC) transformation.