The pyridyltetrazolate ligand formed in situ from NaN3 and 3‐cyanopyridine in the presence of ZnCl2 or CdCl2 in water affords acentric (1) or chiral (2) coordination polymers, respectively. The corresponding reaction of ZnCl2 with 4‐cyanopyridine gives acentric 3 (not shown). Compounds 1–3 are second harmonic generation active.

The rational design and construction of hybrid organic ± inorganic zeolite analogues (HOIZAs) for enantioseparation and catalysis is of intense current interest. These solids have shown their potential to control the host ± guest chemistry of the framework by tailoring or tuning the chemical building blocks from which the network is assembled. [1±6] Through the incorporation of appropriate organic ligands the polarity of an intraframework void may be tuned to attract a range of guest molecules. This potential is not available with pure inorganic zeolites. [1] The inclusion of enantiomerically pure chiral building blocks into microporous materials (zeotypes) for enantiomer separation, as well as chiral synthesis and catalysis, has been a continuing challenge and represents an ambitious goal for chemists. [2±4] Currently known materials capable of offering enantiomeric separation and catalysis tend to be 2D layer-type structures that are able to intercalate guests. [1,5] Attempts to resolve enantiomers using zeolite beta, one polymorph of which crystallizes in the chiral space group P4 1 22, have as yet been unsuccessful. [6] It is known that some 3D metal coordination polymers, such as chiral coordination polymers, can reversibly exchange guest molecules while maintaining crystallinity. [7±22] These materials, however, are constructed from achiral building blocks. As a consequence, the product is a racemic mix of crystals, although their single crystals are enantiomeric. Enantiomerically pure HOIZAs with intraframework voids capable of accommodating guest molecules are highly desirable. Ideally, such a 3D framework should have relatively high thermal stability and rigidity, and possess channels that permit reversible inclusion of guests. To the best of our knowledge the existence of chiral 3D HOIZAs capable of resolving racemic guest molecules by the reversible inclusion/removal of guests is unknown. Here we report a robust 3D enantiopure HOIZA capable of resolving racemic mixtures of small organic molecules.Our strategies employed in preparing such a material involve the rational design and use of functionalized chiral ligands that are capable of bridging metal centers to form an open framework. Specifically, such a framework is produced in a self-assembly process by linking cationic metal centers and an enantiopure chiral bridging ligand containing the following functional groups: 1. A carboxylate binding group that makes the ligand anionic and the framework neutral. This ensures that intraframework voids are not occupied by counterions. 2. A mix of hydrophobic and hydrophilic groups that induce the inclusion of a variety of guests. 3. A pyridyl-type group that is able to satisfactorily complete the coordination sphere of the metal center in the generation of a 3D diamondoid coordination polymer. [23±27] One candidate that fulfils these requirements is quitenine (6'-methoxyl-(8S,9R)-cinchonan-9-ol-3-carboxylic acid (HQA)). The enantiopure chiral building block HQA, which is prepared from the off-the-shelf ...

No abstract

The in situ hydrothermal reactions of ZnCl(2) with benzonitrile, 2-amino-5-cyanopyridine, and trans-2,3-dihydro-2-(4' '-cyanophenyl)-benzo[e]indole in the presence of NaN(3) and water afford two 3D-diamond-like networks, (CN(4)-C(6)H(5))(2)Zn (1) and (NH(2)-C(5)H(3)N-CN(4))(2)Zn (2), and one 2D square grid network, [(CN(4)-C(6)H(4)-C(12)H(7)N-C(5)H(4)N)(2)Zn].1.5H(2)O (3), in which these ligands gradually involve a noncenter-A-D (acceptor-donor) system, a one-center-A-D system, and a two-center-A-D system, respectively. All three compounds crystallize in noncentrosymmetric space groups (I2d for 1 and 2 and Fdd2 for 3) and display strong second harmonic generation (SHG) responses. Among the three new complexes, 3 shows the largest SHG effect, which is about 50 and 500 times that of urea and KDP (KH(2)PO(4)), respectively. The two-center-A-D system (multicenter push-pull electronic effect) in 3 may be responsible for it having the largest SHG effect. Interestingly, the three compounds exhibit strong fluorescent emissions at different wavelengths, 1 and 2 with blue fluorescent emissions at 390 and 415 nm and 3 with yellow-green fluorescent emissions at 495 and 532 nm.

The quest for the single-molecular magnets (SMMs) based on mononuclear transition-metal complexes is focused on the low-coordinate species. No transition-metal complex with a coordination number of eight has been shown to exhibit SMM properties. Here the magnetic studies have been carried out for a mononuclear, eight-coordinate cobalt(II)-12-crown-4 (12C4) complex [Co(II)(12C4)2](I3)2(12C4) (1) with a large axial zero-field splitting. Magnetic measurements show field-induced, slow magnetic relaxation under an applied field of 500 Oe at low temperature. The magnetic relaxation time τ was fitted by the Arrhenius model to afford an energy barrier of Ueff = 17.0 cm(-1) and a preexponential factor of τ0 = 1.5 × 10(-6) s. The work here presents the first example of the eight-coordinate, mononuclear, 3d metal complex exhibiting the slow magnetic relaxation.