Site‐Selective Ligand Exchange on a Heteroleptic Ti^IV Complex Towards Stepwise Multicomponent Self‐Assembly

Abstract

A series of heteroleptic [Ti1(2)X](-) complexes have been selectively constructed from a mixture of Ti(IV) ions, a pyridyl catechol ligand (H(2)1; H(2)1=4-(3-pyridyl)catechol), and various bidentate ligands (HX) in the presence of a weak base, in addition to a previously reported [Ti1(2)(acac)](-) (acac=acetylacetonate) complex. Comparative studies of these Ti(IV) complexes revealed that [Ti1(2)(trop)](-) (trop=tropolonate) is much more stable than the [Ti1(2)(acac)](-) complex, which allows the replacement of acac with trop on the [Ti1(2)(acac)](-) complex. This Ti(IV)-centered site-selective ligand exchange reaction also takes place on a heteronuclear Pd(II)-Ti(IV) ring complex with the preservation of the Pd(II)-centered coordination structures. Intra- and intermolecular linking between two Ti(IV) centers with a flexible or a rigid bis-tropolone bridging ligand provided a tetranuclear and an octanuclear Pd(II)-Ti(IV) complex, respectively. These higher-order structures could be efficiently constructed only through a stepwise synthetic route.

From Hierarchical Helicates to Functional Supramolecular Devices

“…[7,8] Related cluster helicates in which the bridging proceeds not by isolated metal ions but by small metal oxide clusters have been also published. [9] In particular,t he complexes 6 describedb yRaymond [10] and 7 by Shionoya [11] should be mentioned here. They are titanium(IV)-triscatecholate-based hierarchically formed helicates, in which the connection of two complexes occurs through pendant phosphane or pyridine side groups coordinating to bridging palladium(II)c omplex units.…”

Tropolone as a High‐Performance Robust Anchoring Group for Dye‐Sensitized Solar Cells

“…[8] Ar esonance structure,t he aromatic tropylium ion, contributes to the electronic structure of tropolones (Scheme 1). In this respect, tropolones can act as an electronwithdrawing motif in p systems.R eports based on the use of tropolones as the key motif of functional molecules are still limited, whereas metal complexes of tropolones have been employed as building blocks for supramolecular coordination complexes [9] and stable liquid crystals. [10] Fore xample,S hioScheme 1.…”

Sequential, Kinetically Controlled Synthesis of Multicomponent Stereoisomeric Assemblies

“…[2] In contrast, self-assembled products in nature almost always arise according to the most expedient reaction pathway, that is, the kinetically selected. [3] Herein we demonstrate a kinetically controlled approach to self-assembly, in which the sequence of addition [4] of molecular structural units leads to the stereoselective formation of metallosupramolecular isomers.…”