Lanthanum-Centered Organotin Oxysulfide Clusters with Substitutable Coordinating Amide Solvent Molecules for Tuning Blue Light Emission

Three novel heterometallic oxysulfide clusters with different coordination small organic molecules have been solvothermally synthesized and structurally characterized, i.e., [(nBuSn)3La(DTT)3(DETA)(L)] (nBuSn = n-butyltin; DTT = 1,4-dithiothreitol; DETA = diethylenetriamine; L = N,N-dimethylformamide (DMF) (1), N-methyl pyrrolidone (NMP) (2), and N-methyl formanilide (MFA) (3)). These clusters are a bowl-shaped structure, composed of a central DETA-coordinated La3+ cation fixed in the triangle ring, [(nBuSn)3(DTT)3], and an amide molecule bonded to La3+ confined inside the bowl. The coordinated amides can be changed and served as a molecular regulator to optimize the microsteric interaction between the clusters and further the physicochemical property. Remarkably, the crystals of 1 exhibit strong blue-violet light emission with the photoluminescence quantum yield (PLQY) of 3.69%, which significantly exceeds than that of 2 and 3 and most of the other organotin oxysulfide clusters. Theoretical calculations and Hirshfeld surface analyses indicate that the weak amide-oriented intercluster interactions of the compounds can regulate their photoluminescence (PL) efficiency. This work provides a paradigm to reveal the relationships between its PL and structurally fine-tuned coordination species.