Multi‐layer 3D Chirality and Double‐Helical Assembly in a Copper Nanocluster with a Triple‐Helical Cu₁₅ Core

Abstract

Conceptually mimicking biomolecules' ability to construct multiple-helical aggregates with emergent properties and functions remains a long-standing challenge. Here we report an atom-precise 18-copper nanocluster (NC), Cu 18 H(PET) 14 (TPP) 6 (NCS) 3 (Cu 18 H) which contains a pseudo D 3 -symmetrical triple-helical Cu 15 core. Structurally, Cu 18 H may be also viewed as sandwich type of sulfur-bridged chiral copper cluster units [Cu 6 À Cu 6 À Cu 6 ], endowing three-layered 3D chirality. More importantly, the chiral NCs are aggregated into an infinite double-stranded helix supported by intra-strand homonuclear CÀ H•••HÀ C dihydrogen contacts and inter-strand CÀ H/π and CÀ H/S interactions. The unique multi-layered 3D chirality and the doublehelical assembly of Cu 18 H are evocative of DNA. Moreover, the collective behaviours of the aggregated NCs not only exhibit crystallization-induced emission enhancement (CIEE) and aggregation-induced emission enhancement (AIEE) effects in the deep-red region, but also efficiently catalyze electron transfer (ET) reaction. This study thus presents that hierarchical assemblies of atomically defined copper NCs could be intricate as observed for important biomolecules like DNA with emergent properties arising from aggregated behaviours.

Advances in Cu nanocluster catalyst design: recent progress and promising applications

“…Dong et al recently reported Cu 18 H(PET) 14 (PPh 3 ) 6 (isothiocyanate) 3 NC and its effectivity toward the reduction of ferricyanide. 67 The structure is visualized as a conventional core–shell structure which consists of a triple-helical Cu 15 core and [(Cu isothiocyanate) 3 (PET) 14 (PPh 3 ) 6 ] shell. They observed that the clustered NCs display photoluminescence emission in the deep-red spectrum and, in addition, exhibit impressive efficacy in catalyzing electron transfer reactions.…”

From Helices to Crystals: Multiscale Representation of Chirality in Double-Helix Structures

“…This is commonly found in the secondary structure of biological macromolecules, , such as the conversion of l -amino acids into proteins with α-helical DNA or a d -nucleotide into P -helical DNA . In the synthesis system, chemists also realize the biomimetic assembly from the small molecules to secondary structures through various noncovalent interactions, , such as π–π interactions, , hydrogen bonds, , and other noncovalent interactions. − This process results in chirality transfer from the microscale to the mesoscale. − The chiral secondary structures (like helices) had a mesochirality similar to the screw dislocations, which are considered crucial in the chiral Te nanocrystals . Therefore, based on the appropriate chiral secondary structure assembly, it is anticipated that a continuous chiral transfer can be achieved, progressing from the microscale to the mesoscale, and ultimately to the macroscale.…”

Homohelical Self-Assembly of Trimer of α-Cyclodextrin and Octamolybdate

“…Owing to the lack of precise structural information about the NPs, it remains a great challenge to accurately identify the assembled array of synthetic NPs. Some nanoclusters can be used as well-defined nanobuilding blocks to assemble into double-stranded helices. − Endowing chiral clusters or chiral building blocks is a prerequisite for the construction of homohelical assemblies. However, the synthesis of chiral clusters is still a challenge. , …”