Self-assembly of an achiral acceptor of square-planar Pd(II) or Pt(II) ion with a symmetric donor generally yields achiral architecture or a racemic mixture of chiral assemblies. Selective formation of an enantiopure assembly in such processes is very challenging. We report here a new approach of converting a dynamic mixture of multiple homochiral assemblies to an enantiopure architecture through the interaction of a chiral guest molecule. One-pot reaction of a cationic C 3 -symmetric tripyridyl donor L•HNO 3 with cis-[(tmeda)Pd(NO 3 ) 2 ] (M) [tmeda = N,N,N′,N′-tetramethylethane-1,2-diamine] yielded a complex mixture of stereoisomers of a chiral octahedral cage. Surprisingly, the presence of R-BINOL as a chiral guest in the above self-assembly induced selective formation of a single enantiopure octahedral cage. S-BINOL induced formation of the other enantiomer of the cage selectively. While selective recognition of an enantiomeric guest from a racemic mixture by a chiral host is well-known, present observation of "reverse chiral recognition" where the guest molecule determines the handedness of the host leading to the formation of an enantiopure cage is noteworthy.

Restriction in intramolecular motions (RIM) is fundamental for the high emission of Aggregation-induced emission (AIE)-active molecules in aggregates or solid-state. However, they are weakly emissive in dilute solution which limits...

A conformationally flexible tetrapyridyl ligand L was assembled separately with three cis-blocked 90° PdII acceptors (M1, M2, and M3) containing different blocking diamines. Surprisingly, different conformations of the donor L were arrested by the acceptors depending on the nature of the blocking amine, leading to the formation of isomeric Pd6 barrels (B1, B2, and B3). B2 and B3 with larger windows have been used to encapsulate polyaromatic hydrocarbons.

Supramolecular systems with sequential energy transfer have prospects in designing artificial light-harvesting systems (LHSs), which can mimic natural photosynthesis process. Here, we report a facile synthesis of a supramolecular coordination polymer (SCP) P as an emissive material through two-component coordination-driven self-assembly of a tetra-imidazole donor (L) containing tetraphenylethene backbone with a 180° trans-[Pt(PEt3)2(OTf)2] acceptor. P shows considerable enhancement in its emission in 90% water–DMSO mixture as it further self-assembles into spherical nanoaggregates. In addition, because of the framework structure of P with hydrophobic cavities and the interspaces present in the nanoaggregates of P, it can act as a suitable host to adsorb organic dyes. Therefore, polymeric material P in the nanoaggregate form in aqueous–DMSO medium was used as an efficient platform to fabricate two highly efficient light-harvesting materials with rare two-step cascade energy-transfer process. For the first-step energy-transfer process, P acts as an efficient energy donor by the Förster resonance energy-transfer (FRET) process to Eosin Y (EY) and Fluorescein (Fl) with high energy-transfer efficiency (58.8% for P-EY and 67.9% for P-Fl), good antenna effect (7.2 for P-EY, 5.2 for P-Fl), and increased quantum yield. Moreover, NiR (Nile Red) was used as a second acceptor to construct efficient two-step artificial light-harvesting materials (P-EY-NiR and P-Fl-NiR), which exhibit high FRET efficiencies of 68.5 and 76.2% as well as good antenna effect of 10.9 and 17.7, respectively. These light-harvesting materials represent the new examples of artificial LHSs based on nanoaggregates of an SCP with sequential two-step energy transfer in aqueous medium. Notably, emission/visual color changes from blue to yellow to pink for P-EY-NiR and blue to green to pink for P-Fl-NiR and cover the entire visible range spectrum.

An emissive Pt(II) coordination polymer (TBP) was synthesized by assembling a benzothiadiazole-based Pt(II) acceptor (A) with tetraphenylethene (TPE) containing donor (L). Multiple benzothiadiazole units in the polymeric array of the...