A “Molecular Pivot-Hinge” Based on the pH-Regulated Intramolecular Switching of Pt−Pt and π−π Interactions

Abstract

The binuclear cycloplatinated complex {[Pt(L)]2(mu-dppm)}2+ (1), where HL is a new cyclometalating ligand 2-phenyl-6-(1H-pyrazol-3-yl)pyridine, is found to behave as a molecular pivot-hinge in which the closing and opening of the hinge is effected by the reversible formation and cleavage of the Pt-Pt d8-d8 interaction and the intramolecular pi-pi interaction mediated by the protonation/deprotonation of the 1-pyrazolyl-NH on the cyclometalating ligand L.

Recent Advances in Phosphorescent Pt(II) Complexes Featuring Metallophilic Interactions: Properties and Applications

“…103 Their strategy stems from the ability of this class of emitting Pt derivative to establish intermolecular Pt£Pt and ππ interaction as a consequence of the presence of the pH-sensitive NH moiety on the coordinated pyrazole unit. 104 Varying the substituent on the ancillary isocyanide group, the assemblydisassembly behavior via metallophophilic interaction upon pH modification was used, on one hand, for the formation of supramolecular hydrogel with bathochromically shifted 3 MMLCT emission and controlled release of cytotoxic complexes; on the other hand, for the selective imaging of lysosomes using aggregated red-emitting species predominant at such low physiological pH (pH ca. 5).…”

Palladium(II) and platinum(II) complexes with N1-hydroxyethyl-3,5-pyrazole derived ligands

“…Calc. for C 24 H 28 N 4 O 2 PdCl 2 (581.8): C,49.60;H,4.85;N,9.63. Found: C,49.37;H,4.62;N,9.32% (2) Suitable crystals for X-ray diffraction of L2 ligand were obtained through crystallisation from ethyl acetate solution, and for compounds, trans-[PdCl 2 (L1) 2 ] (1) and trans-[PdCl 2 (L2) 2 ] (2) were obtained through crystallisation from a chloroform solution.…”

Movements Related to Opening, Closing, and Translocation Function

“…On protonation of both the pyridine substituents, the preferred rotameric conformation is the one in which the pyridinium groups are rotated away from the stacked conformation [135]. A binuclear cyclometalated complex, in which Pt(II) is coordinated by a C,N,N-pyrazol ligand, mimics the mechanical motion of a pivot hinge [137]. A binuclear cyclometalated complex, in which Pt(II) is coordinated by a C,N,N-pyrazol ligand, mimics the mechanical motion of a pivot hinge [137].…”