Heteroleptic NIR-Emitting YbIII/Anilate-Based Neutral Coordination Polymer Nanosheets for Solvent Sensing

Ashoka Sahadevan, Suchithra

First

;Monni, Noemi;OGGIANU, MARIANGELA;Abhervé, Alexandre;Marongiu, Daniela;Saba, Michele;Mura, Andrea;Bongiovanni, Giovanni;Mameli, Valentina;Cannas, Carla;Avarvari, Narcis;Quochi, Francesco;Mercuri, Maria Laura

2020-01-01

---

Abstract

Nanosheets of two mixed linker (anilate/carboxylate)/YbIII-based two-dimensional (2D) layered coordination polymers (CPs) are herein reported. Bulky sized CPs, formulated as [Yb4(ClCNAn)5(DOBDC)1(DMSO)10]n·(DMSO)2 (1) and [Yb2(ClCNAn)2(F4BDC)(DMSO)6]n (2), are formed by two-dimensional neutral polymeric networks based on YbIII ions, heterosubstituted ClCNAn2- anilate, and dicarboxylate linkers (DOBDC2- in 1; F4BDC2- in 2): in 1, neighbor layers are eclipsed and form six-membered rings showing either hexagonal cavities, formed by ClCNAn2- and YbIII ions or rectangular cavities formed by ClCNAn2-, DOBDC2-, and YbIII while distorted square-like cavities formed by ClCNAn2-, F4BDC2-, and YbIII are obtained in 2. The 1 and 2 nanosheets, that is, 1-NS and 2-NS, are produced by exfoliation of bulk CPs by the well-known top-down approach and characterized by atomic force microscopy and high resolution transmission electron microscopy. The 1-NS and 2-NS show thickness in the range of 1-5 nm, whereas the lateral dimensions are in the micrometer scale and the presence of well-defined lattice fringes, key evidence of their robustness. Remarkably the powder X-ray diffraction (PXRD) patterns highlight that the crystallinity is retained at the nanoscale level. Nanosheets photophysics are investigated by an innovative Multiprobe Approach where lifetime, photoluminescence (PL) and integrated PL are simultaneously measured in order to study how these parameters can be affected by the presence of the different ligands. These advanced photophysical studies pave the way to challenging luminescent sensing applications and to contribute to the ongoing research on fabricating robust and crystalline hybrid (organic/inorganic) lanthanide sheetlike 2D nanomaterials.