| Abstract
| - A class of molecular host complexes, modified metal dibenzoylmethanates (DBM), is extended to dimeric, trimeric, and polymeric host receptors by bridging metal DBM units with 4,4‘-dipyridyl.
- Recently reported molecular host complexes, modified metal dibenzoylmethanates (metalDBMs), are extended to polynuclear host receptors by connecting metal DBM units withbridging ligand 4,4‘-dipyridyl (bipy). Series of new solvent-free as well as inclusion materialswere prepared and studied with XRD, NMR, and other methods. Template-directed synthesisgave inclusion compounds with three distinct types of host receptors: dimeric [Zn2(bipy)(DBM)4], trimeric [Zn3(bipy)2(DBM)6], and polymeric [Zn(bipy)(DBM)2]n complexes. Thedimeric complex was isolated as a solvent-free compound and as inclusion compounds withtert-butylbenzene and fluorobenzene (host per guest molar ratios of 1:1 and 1:2/3, respectively).The trimeric complex was prepared as an inclusion compound with DMSO (1:5 molar ratio).The polymeric complex was observed in inclusion compounds with fluorobenzene (host unitper guest molar ratio 1:2), tetrahydrofuran (1:2), 2-pentanone (1:2), bipy/DMSO (1:1/2:1/2),and bipy/tert-butylbenzene (1:1:2); a solvent-free material was obtained upon desolvation oftetrahydrofuran and 2-pentanone inclusions. The isolated host species have five-coordinatedterminal zinc centers (two chelating DBMs and a singly coordinating bipy) and octahedrallycoordinated intrinsic zinc centers (two chelating equatorial DBMs and two singly coordinatingbipys). The bipy ligands bridge the zinc centers to give the di-, tri-, and polynuclear complexes.Nanosized voids between the DBM units coordinated to adjacent zinc centers form the basisfor cages and channels in the inclusion materials. These voids have, in many cases, a typicalsize of between 1 and 2 nm and accommodate up to five molecules per single cavity or tworows of guest molecules in a single channel. When compared to previously reported metalDBMs, the multinuclear metal DBM receptors reported here exhibit stronger inclusionaffinity and enhanced inclusion capacity.
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