Volume 63, Issue 6 e202317345
Research Article

Modulation of Singlet-Triplet Gap in Atomically Precise Silver Cluster-Assembled Material

Priyanka Chandrashekar

Priyanka Chandrashekar

School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Kerala, 695551 India

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Gopa Sardar

Gopa Sardar

Department of Physics, Indian Institute of Technology Bombay Powai, Mumbai, 400076 India

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Dr. Turbasu Sengupta

Dr. Turbasu Sengupta

Department of Physics, Virginia Commonwealth University, Richmond, VA-23220 USA

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Dr. Arthur C. Reber

Dr. Arthur C. Reber

Department of Physics, Virginia Commonwealth University, Richmond, VA-23220 USA

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Dr. Pradip Kumar Mondal

Dr. Pradip Kumar Mondal

Elettra-Sincrotrone Trieste, S.S. 14 Km 163.5 in Area Science Park, Basovizza, 34149 Trieste, Italy

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Prof. Dinesh Kabra

Prof. Dinesh Kabra

Department of Physics, Indian Institute of Technology Bombay Powai, Mumbai, 400076 India

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Prof. Shiv N. Khanna

Corresponding Author

Prof. Shiv N. Khanna

Department of Physics, Virginia Commonwealth University, Richmond, VA-23220 USA

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Dr. Pravas Deria

Corresponding Author

Dr. Pravas Deria

School of Chemical & Biomolecular Science, Southern Illinois University, 1245 Lincoln Drive, Carbondale, IL-62901 USA

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Prof. Sukhendu Mandal

Corresponding Author

Prof. Sukhendu Mandal

School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Kerala, 695551 India

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Dedicated to Professor C. N. R. Rao on the occasion of his 90th birthday
First published: 11 December 2023
Citations: 21

Graphical Abstract

The singlet-triplet energy gap was modulated by controlling the inter-cluster interaction defined by the supramolecular arrangements of Ag12 nanoclusters.

Abstract

Silver cluster-based solids have garnered considerable attention owing to their tunable luminescence behavior. While surface modification has enabled the construction of stable silver clusters, controlling interactions among clusters at the molecular level has been challenging due to their tendency to aggregate. Judicious choice of stabilizing ligands becomes pivotal in crafting a desired assembly. However, detailed photophysical behavior as a function of their cluster packing remained unexplored. Here, we modulate the packing pattern of Ag12 clusters by varying the nitrogen-based ligand. CAM-1 formed through coordination of the tritopic linker molecule and NC-1 with monodentate pyridine ligand; established via non-covalent interactions. Both the assemblies show ligand-to-metal-metal charge transfer (LMMCT) based cluster-centered emission band(s). Temperature-dependent photoluminescence spectra exhibit blue shifts at higher temperatures, which is attributed to the extent of the thermal reverse population of the S1 state from the closely spaced T1 state. The difference in the energy gap (ΔEST) dictated by their assemblies played a pivotal role in the way that Ag12 cluster assembly in CAM-1 manifests a wider ΔEST and thus requires higher temperatures for reverse intersystem crossing (RISC) than assembly of NC-1. Such assembly-defined photoluminescence properties underscore the potential toolkit to design new cluster- assemblies with tailored optoelectronic properties.

Conflict of interest

The authors declare no conflict of interest.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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