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چکیده
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A supramolecular coordination polymer [Pb(HL’)(H2O)(SCN)]2(ClO4)2·4H2O, prepared via a one-pot reaction of N’-isonicotinoylpicolinohydrazonamide (HL) with Pb(ClO4)2 and KSCN, is reported. The Pb2+ cation is N,N’,O-coordinated by the ligand HL’, which is a zwitterionic form of HL characterized by a deprotonated amide and a protonated 4-pyridine N atoms, and by the thiocyanate S atom, yielding a [Pb(HL’)(SCN)]+ cation. A pair of these cations linked by two Pb–Namide bonds, yielding a [Pb(HL’)(SCN)]22+ cation. The latter cations are linked by the Pb···SCN tetrel bonds. The coordination sphere of the metal cation is completed by the Pb···O tetrel bond with one of the crystal water molecules. This results a supramolecular cationic network with hcb topology. The structure is further stabilized by π···π stacking between aromatic rings and interconnected via an array of O–H···O and N–H···O hydrogen bonds involving ClO4– ions and H2O molecules. Both HL and derived coordination compound were found to be emissive in MeOH with the CIE-1931 chromaticity coordinates of (0.262, 0.370) and (0.369, 0.482), respectively, falling within the green and yellow-green gamut of the chromaticity diagram. The DFT studies revealed the dual nature of the Pb···S and Pb···N interactions, highlighting their semicoordinative and noncovalent characteristics, respectively. Electrostatic potential and QTAIM analyses confirm the presence of σ-holes at the Pb2+ cation, aligning with observed bonding motifs. This research elucidates the synergistic relationship between coordination bonds and noncovalent forces in guiding the construction of extended supramolecular polymers.
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