Nanosheets of two mixed linker (anilate/carboxylate)/Yb III -based two-dimensional (2D) layered coordination polymers (CPs) are herein reported. Bulky sized CPs, formulated as [Yb 4 (ClCNAn) 5 (DOBDC) 1 (DMSO) 10 ] n •(DMSO) 2 (1) and [Yb 2 (ClCNAn) 2 (F 4 BDC)(DMSO) 6 ] n (2), are formed by twodimensional neutral polymeric networks based on Yb III ions, heterosubstituted ClCNAn 2− anilate, and dicarboxylate linkers (DOBDC 2− in 1; F 4 BDC 2− in 2): in 1, neighbor layers are eclipsed and form six-membered rings showing either hexagonal cavities, formed by ClCNAn 2− and Yb III ions or rectangular cavities formed by ClCNAn 2− , DOBDC 2− , and Yb III while distorted square-like cavities formed by ClCNAn 2− , F 4 BDC 2− , and Yb III 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 wellknown 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.

The synthesis, structural characterization, photophysical studies, and exfoliation of two-dimensional (2D) layered coordination polymers, formulated as {[Ln2(ClCNAn)3(DMF)6]·(DCM) x } n (Ln­(III) = Yb­(x = 0), Nd, and Er (x = 2)) based on the heterosubstituted chlorocyananilate ligand, are reported. These compounds consist of neutral polymeric 2D networks of the chlorocyananilate ligand alternating with Ln­(III) ions. They form six-membered rings with rectangular cavities, where neighbor layers are eclipsed along the a axis (Yb), and a regular honeycomb-like structure, with hexagonal cavities filled by dichloromethane solvent molecules (Nd and Er), where neighbor layers alternate along the c axis. Several interlayer interactions between lanthanide centers and dimethylformamide molecules, facing the cavities, are present in all compounds. Free-standing nanosheets, obtained by a top-down strategy involving sonication-assisted solution synthesis and characterized by atomic force microscopy and high-resolution transmission electron microscopy, show lateral dimensions on the micrometer scale, thicknesses down to the monolayer, and the presence of lattice fringes. Time-resolved photoluminescence studies performed on both the bulk and nanosheets clearly demonstrate that the chlorocyananilate ligand acts as an efficient antenna toward Ln­(III) ions and that emission sensitization occurs as a multistep relaxation process involving, in sequence, intersystem crossing and energy transfer from ligand triplet states to the Ln­(III) ions. Effects induced by the exfoliation process on the photophysical properties of the nanosheets are also discussed.

The mixed-valence FeFe 2D coordination polymer formulated as [TAG][FeFe(ClCNAn)]·(solvate) 1 (TAG = tris(amino)-guanidinium, ClCNAn = chlorocyanoanilate dianionic ligand) crystallized in the polar trigonal space group P3. In the solid-state structure, determined both at 150 and at 10 K, anionic 2D honeycomb layers [FeFe(ClCNAn)] establish in the ab plane, with an intralayer metal-metal distance of 7.860 Å, alternating with cationic layers of TAG. The similar Fe-O distances suggest electron delocalization and an average oxidation state of +2.5 for each Fe center. The cation imposes its C symmetry to the structure and engages in intermolecular N-H···Cl hydrogen bonding with the ligand. Magnetic susceptibility characterization indicates magnetic ordering below 4 K and the presence of a hysteresis loop at 2 K with a coercive field of 60 Oe. Mössbauer measurements are in agreement with the existence of Fe(+2.5) ions at RT and statistic charge localization at 10 K. The compound shows semiconducting behavior with the in-plane conductivity of 2 × 10 S/cm, 3 orders of magnitude higher than the perpendicular one. A small-polaron hopping model has been applied to a series of oxalate-type FeFe 2D coordination polymers, providing a clear explanation on the much higher conductivity of the anilate-based systems than the oxalate ones.

A series of two-dimensional (2D)-layered coordination polymers (CPs) based on the heterosubstituted anilate ligand ClCNAn 2− derived from 3-chloro-6-cyano-2,5-dihydroxybenzoquinone and Dy III are reported. By changes in the synthetic methods (layering technique, solvothermal or conventional one-pot reactions) and conditions (solvent, concentration, etc.), different types of 2D extended networks could be prepared and structurally characterized. Compounds 1 a n d 1 ′ , t w o p o l y m o r p h s w i t h t h e f o r m u l a [Dy 2 (ClCNAn) 3 (DMSO) 6 ] n •(H 2 O) x [x = 7 (1), 0 (1′)], were prepared by a conventional one-pot reaction and recrystallized at different concentrations. Compound 2, formulated as [Dy 2 (ClCNAn) 3 (DMF) 6 ] n , was prepared by a layering technique, while compound 3, formulated aswas obtained by a solvothermal method. Compounds 1 and 2 are neutral 2D CPs of the ClCNAn 2− ligand and Dy III ions, while 3 presents 2D anionic layers of [Dy 2 (ClCNAn) 4 (H 2 O) 2 ] 2− alternating with cationic layers of Me 2 NH 2 + ions. These compounds show very diverse networks, with compound 1 forming 2D (8,3) and (4,3) topology with eight-and four-membered rings with square cavities, 1′ and 2, respectively, a 2D (6,3) topology with six-membered rings (a rectangular cavity for 1′ and a regular hexagonal cavity for 2), and 3 a 2D (4,4) topology with distorted square cavities. In this respect, 1 and 1′ represent the first examples of polymorphism in the family of anilate-based CPs. Thermal analysis measurements (differential scanning calorimetry and thermogravimetry) show an exothermic polymorphic transformation from the kinetically stable 1′ phase to the thermodynamically stable phase 1. The magnetic behavior of 1−3 very likely indicates depopulation of the m J levels, while the presence of weak antiferromagnetic coupling between the Dy III centers mediated by the anilate bridge cannot be excluded.

A novel anilato-based 3D ultramicroporous MOF is reported, displaying a significant balance of high CO2 separation from CO2:N2 and CO2:CH4 gas mixtures, high thermal stability and high regenerability, a challenge in the separation technology industry.