Polymorphism of [Cu15(PhCH2CH2S)13(PPh3)6][BF4]2 and Double-Helical Assembly of [Cu18H(PhCH2CH2S)14(PPh3)6Cl3]: Origin of Two Chiral Nanoclusters with Triple-Helical Core from Intermediates

Creators: Nag, Abhijit¹; Butt, Abdul Mannan¹; Yang, Moon Young²; Managutti, Praveen B.¹; Pirzada, Bilal Masood¹; Mohideen, M. Infas H.¹; Abdelhady, Ahmed L.¹; Haija, Mohamed Abu¹; Mohamed, Sharmarke¹; Merinov, Boris V.²; Goddard, William Andrew²; Qurashi, Ahsanulhaq¹

1. Khalifa University of Science and Technology
2. California Institute of Technology

Abstract

Here, we report the solvent-induced polymorphism in [Cu15(PET)13(TPP)6][BF4]2(Cu15) (TPP = triphenylphosphine, PET = 2-phenylethanthiol), and double-helical assembly of the [Cu18H(PET)14(TPP)6Cl3] (Cu18) nanocluster (NC) from reaction intermediates. Both copper NCs have an intrinsically chiral triple-stranded helicate metal core, unlike traditional copper NCs with a polyhedral-based kernel. The chiral structure of Cu15 resembles an enantiomeric pair in the unit cell. Moreover, Cu18 has a three-layered 3D chirality of a sandwich constructed of sulfur-bridged copper NCs aligned in a top-middle-down configuration. Furthermore, the Cu18 NC self-hierarchically assembles into a complex double-stranded helix secondary structure sustained by noncovalent interactions. Electrospray ionization mass spectrometry (ESI-MS), density functional theory (DFT), and X-ray photoelectron spectroscopy (XPS) were utilized to validate the single-crystal X-ray diffraction (SCXRD) data. Overall, this study provides an interesting example of polymorphism, chirality, and hierarchical double-helical assembly of NCs, allowing for extensive understanding of complicated structures at the atomic level.

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Acknowledgement

The author acknowledges Khalifa University of Science and Technology for providing laboratory facilities and instrumentation throughout this research. The authors would like to express their gratitude for the support received from the AMCC and the Chemistry Department at Khalifa University of Science and Technology. W.A.G., M.Y.Y., and B.V.M. were supported by the U.S. National Science Foundation (No. CBET 2311117).

Contributions

CRediT: Abhijit Nag data curation, formal analysis, investigation, methodology, validation, visualization, writing - original draft, writing - review & editing; Abdul Mannan Butt investigation, methodology, validation, visualization, writing - original draft, writing - review & editing; Moon Young Yang investigation, software, validation, visualization, writing - original draft, writing - review & editing; Praveen B Managutti software, validation, visualization, writing - review & editing; Bilal Masood Pirzada methodology, resources, validation, visualization, writing - review & editing; M. Infas Haja Mohideen conceptualization, project administration, validation, visualization, writing - review & editing; Ahmed L. Abdelhady supervision, validation, visualization, writing - review & editing; Mohammad Abu Haija project administration, validation, visualization, writing - review & editing; Sharmarke Mohamed software, validation; Boris V. Merinov data curation, software, supervision, validation, visualization, writing - review & editing; William A. Goddard III formal analysis, project administration, resources, software, supervision, validation, visualization, writing - review & editing; Ahsanulhaq Qurashi conceptualization, data curation, formal analysis, funding acquisition, project administration, resources, supervision, validation, visualization, writing - review & editing.

Supplemental Material

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsmaterialslett.4c02148.

CIF data for Cu₁₈ (PDF)
CIF data for Cu₁₅ (PDF)
Crystallographic structure of the Cu₁₈ nanocluster (CIF)
Crystallographic structure of the Cu₁₅ nanocluster (CIF)
Three-dimensional image of the Cu₁₅ nanocluster (MP4)
Details regarding synthesis, instrumentation and characterization, including ESI-MS, X-ray crystallography, XPS, and DFT calculations; Figures S1–S12 and Tables S1–S3 (PDF)

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