Imidazole H-Complexes with Proton-Acceptor Molecules from the Data of IR Spectroscopy and Quantum-Chemical Calculations

Assemble–Disassemble–Reassemble Dynamics in Copper Nanocluster-Based Superstructures

“…The N1−H group of imidazole (of 4-PIT) is known to form H-bond complexes with proton acceptor solvents like DMF, acetonitrile (ACN), dimethylsulfoxide (DMSO), etc. 50 This H-bonding between 4-PIT and the aprotic polar solvent (like DMF) results in the suppression of ligand−ligand interactions (which initially resulted in the augmentation of the PL intensities of the CuSSs), which is reflected in the fall of PL intensity at ∼590 nm (please refer to Figure 3a). Additionally, the solvatochromic behavior of 4-PIT (please refer to Figure S11) makes it attain an increased PL intensity when the CuSSs were excited at 345 nm in the presence of 80% DMF (please refer to Figure 3a).…”

“…The absorption spectra of only the ligand (4-PIT) under the same reaction conditions, i.e., with increasing DMF content, display a similar red shift in the absorption maxima, as shown in Figure S11. The N1–H group of imidazole (of 4-PIT) is known to form H-bond complexes with proton acceptor solvents like DMF, acetonitrile (ACN), dimethylsulfoxide (DMSO), etc . This H-bonding between 4-PIT and the aprotic polar solvent (like DMF) results in the suppression of ligand–ligand interactions (which initially resulted in the augmentation of the PL intensities of the CuSSs), which is reflected in the fall of PL intensity at ∼590 nm (please refer to Figure a).…”

“…Therefore, this corroborates that interligand H-bonding interactions, along with interligand C–H−π interactions, are responsible for the formation of CuSSs. Upon increasing the content of a proton-accepting solvent, i.e., DMF, the interligand H-bonding interactions get blocked, as DMF is known to form H-bond complexes with the proton at the e position (N1–H) of the imidazole moiety of the ligand 4-PIT . This results in a change in the photophysical signatures of the CuSSs.…”

“…Upon increasing the content of a proton-accepting solvent, i.e., DMF, the interligand H-bonding interactions get blocked, as DMF is known to form H-bond complexes with the proton at the e position (N1−H) of the imidazole moiety of the ligand 4-PIT. 50 This results in a change in the photophysical signatures of the CuSSs. The CuNCs may follow two paths upon changing the solvent environment, as shown in Figure 3f: changing the solvent from polar protic to polar aprotic could lead to the disassembly of the CuNCs, as shown in path (I), or to the complete disintegration of the CuNCs (path (II)).…”