No abstract

Binding benzene: A novel blue luminescent star‐shaped ZnII complex has been found to be able to detect benzene selectively by fluorescent quenching. This is attributed to the compoundapos;s high affinity to benzene, as demonstrated in the crystal structure (see picture; yellow: benzene, red: zinc).

Eight novel three-coordinate boron compounds with the general formula BAr(2)L, in which Ar is mesityl and L is a 7-azaindolyl- or a 2,2'-dipyridylamino-functionalized aryl or thienyl ligand, have been synthesized by Suzuki coupling, Ullmann condensation methods, or simple substitution reactions (L = p-(2,2'-dipyridylamino)phenyl, 1; p-(2,2'-dipyridylamino)biphenyl, 2; p-(7-azaindolyl)phenyl, 3; p-(7-azaindolyl)biphenyl, 4; 3,5-bis(2,2'-dipyridylamino)phenyl, 5; 3,5-bis(7-azaindolyl)phenyl, 6; p-[3,5-bis(2,2'-dipyridylamino)phenyl]phenyl, 7; 5-[p-(2,2'-dipyridylamino)phenyl]-2-thienyl, 8). The structures of 1, 3, and 5-7 have been determined by X-ray diffraction analyses. These new boron compounds are bright blue emitters. Electroluminescent devices using compound 2 or 8 as the emitter and the electron-transport layer have been successfully fabricated. Molecular orbital calculations (Gaussian 98) have established that the blue emission of compounds 1-8 originates from charge transfer between the pi orbital of the ligand L and the p(pi) orbital of the boron center. The ability of these boron compounds to bind to metal centers to form supramolecular assemblies was demonstrated by treatment of compound 2 with Zn(O(2)CCF(3))(2), which generated a 1:1 chelate complex [2.Zn(O(2)CCF(3))(2)] (10), and also by treatment of compound 4 with AgNO(3), yielding a 2:1 coordination compound [(4)(2).Ag(NO(3))] (11). In the solid state, compounds 10 and 11 form interesting head-to-head and tail-to-tail extended structures that host solvent molecules such as benzene.

The reaction of AgX, where X = trifluoroacetate (CF(3)CO(2)(-), tfa), nitrate (NO(3)(-)), trifluoromethanesulfonate (triflate, CF(3)SO(3)(-), OTf), hexafluorophosphate (PF(6)(-)), or perchlorate (ClO(4)(-)), with 2,2',3' '-tripyridylamine (tpa) yields five novel silver(I) complexes, which have been structurally characterized. The five complexes have the same 1:1 stoichiometry of Ag/tpa but exhibit different modes of coordination, depending upon the counterion present in the compound. Compound 1, [Ag(tpa)(tfa)](n)(), forms a 1D coordination polymer of [Ag(tpa)(tfa)](2) dimer units linked through bridging tfa counterions. Compound 2, [Ag(tpa)(CH(3)CN)(NO(3))](n), forms a zigzag chain 1D coordination polymer exclusively through Ag-N bonds. In compounds 1 and 2, each tpa ligand is bound to two Ag(I) ions via a 2-py and a 3-py group. Compound 3, [Ag(tpa)(OTf)](n), forms a ribbonlike 1D coordination polymer, in which each tpa ligand binds to three different silver centers via all three pyridyl groups, and the counterion remains coordinated to the Ag(I) center. Compounds 4, [Ag(tpa)(CH(3)CN)](n)(PF(6))(n), and 5, [Ag(tpa)(CH(3)CN)](n)() (ClO(4))(n), display ribbonlike structures resembling that of 3, except that the counterions are not coordinated. All complexes are luminescent in acetonitrile solution, with emission maxima in the near-UV region (lambda(max) = 366, 368, 367, 367, and 368 nm for 1-5, respectively). At 77 K, the emission maxima are red-shifted to lambda(max) = 452, 453, 450, 450, and 454 nm for 1-5, respectively.

The crystal structure of {[Ni(4,4A-bipyridine) 2 (NO 3 ) 2 ]·2pyr-ene} n reveals the first example of complementary, interpenetrating covalent and noncovalent 2D networks.