Exfoliating a Cd^II–Purine Framework: Conversion of Nanosheets‐to‐Nanofibers and Studies of Elastic and Capacitive Properties

Abstract

Layered bulk crystals are amenable to exfoliation to yield 2D nanosheets through isolation and intercalation processes, which could be further converted to 1D nanoscale structures. The latter inherit gross morphological and physical properties associated with the precursor structures. Herein, we report three purine‐based crystal structures 1, 2, and 3, where 3 is obtained by a single‐crystal‐to‐single‐crystal transformation from 2 and is a conformational polymorph of 1. Next, we describe the sonication‐assisted liquid exfoliation of 1, a CdII–purine coordination framework, into nanosheets and nanofibers in a solvent‐dependent process. The exfoliation was carefully studied at low temperatures to ascertain this unique conversion. This work also features the determination of the Young's modulus and surface potential of the bioinspired CdII‐based nanostructures by using amplitude modulation–frequency modulation atomic force microscopy and Kelvin probe force microscopy, respectively, revealing their interesting elastic and capacitive properties for their possible use in electronics and energy devices. Electron impedance spectroscopy measurements further established a higher value of capacitance for the exfoliated CdII framework as compared to the ligand alone.

Crystal Engineering and Self‐Assembled Nanoring Formation with Purine‐CdII/HgII Supramolecular Frameworks

“…Crystallographic details of L1 and HgCl 2 (1 eq.) has been elaborated in a previous report [22] . It was also noted that 2 eq.…”

“…has been elaborated in a previous report. [22] It was also noted that 2 eq. of HgCl 2 with L1 also gives similar crystal structure.…”

“…However, it was also observed that L1 with one/two equivalents of HgCl 2 resulted in Hg II binding only to N9 whereas N7 remained free due to lack of availability of more Hg II ions in the system, thereby indicating favoured formation of a chelate over N7 binding. [22] Exploring the complexation of HgCl 2 with ligand L2 disclosed that with 2 eq., 3 exhibits binding of Hg II only at N9 position while N3 remains free. Similar crystal structure was observed even after increasing the equivalents to three.…”

“…[11,18,19] The literature showcases several examples where molecular self-assembly has been explored and utilised to develop various applications. A series of nanostructures such as nanosheets, [20] nanowires, [21,22] nanospheres, [23] nanorings [24][25][26][27] etc. have been explored.…”

Single‐platform, Attomolar Detection of Multiple Biomarkers by a Flexible SERS Sensor

“…Step 2 . N9‐(pyridin‐2‐ylmethyl)‐N 6 ‐methoxyadenine(L) was synthesized by nucleophilic attack of O‐methyl hydroxylamine hydrochloride at C6 position of N9‐pyridin‐2‐ylmethyl‐6‐chloropurine using reported method [47] …”