Complexes Zn

Zn-complexes with heterocyclic ligands as fluorescent probes for biological investigations 98CSR179. 

Bromomethyl-6,7-dichloro-2,3-dimethoxyquinoxaline (284) gave 6,7-dichloro-5-(3-chloroacetonyl)-2,4-dimethoxyquinoxaline (285) (by treatment of a derived Zn complex with CICH2COCI in the presence of a Pd complex as catalyst 75%. See original paper for considerable detail. )... 

Reaction of the Zn complex itself with CoClj yields different compounds by ligand transfer , e.g., T7 -CpCo(Et2C2B2Me2S) (83%), (ij -Cp)2Fe (70%) and traces of the triple-decked complex Tj -CpFe- A-(Et2C2B2Me2S)FeCp-i7. ... 

Scheme 68 The molecular hydrogen evolution catalyzed by self-assembled Zn-Fe-Zn complex...

Lewis-Acid Catalyzed. Recently, various Lewis acids have been examined as catalyst for the aldol reaction. In the presence of complexes of zinc with aminoesters or aminoalcohols, the dehydration can be avoided and the aldol addition becomes essentially quantitative (Eq. 8.97).245 A microporous coordination polymer obtained by treating anthracene- is (resorcinol) with La(0/Pr)3 possesses catalytic activity for ketone enolization and aldol reactions in pure water at neutral pH.246 The La network is stable against hydrolysis and maintains microporosity and reversible substrate binding that mimicked an enzyme. Zn complexes of proline, lysine, and arginine were found to be efficient catalysts for the aldol addition of p-nitrobenzaldehyde and acetone in an aqueous medium to give quantitative yields and the enantiomeric excesses were up to 56% with 5 mol% of the catalysts at room temperature.247... 

Diethylenetriamineacetic acid has been used in the formation of homodinuclear zinc complexes with the bridging imidazole. The crystal structure of [LZn(imidazolate)ZnL]C104 was obtained. The magnetics of the heterodinuclear Cu-Zn complex were studied and single crystal EPR of the Zn2 dimer doped with the CuZn dimer.139... 

A pyridine derivative related to dien with respect to the number and distribution of N-donor atoms, namely bis(2-pyridylmethyl)amine (bpma), also gives comparable complexes with Cd, e.g., [Cd(bpma)2](C104)2 with potentially three isomers (including a pair of enantiomers). As shown by the structure analysis (C2/c, Z = 4), a distorted octahedral fac-isomer with symmetry 2 —C2 has been isolated, necessarily with both enantiomers in the crystal lattice. No significant difference in the two kinds of Cd—N bonds (rav(Cd—N) 235.0 pm) is observed.189 Solid-state 13C NMR spectra of this complex and related Mn and Zn complexes have been discussed. 

Soil solution to soil ratios also strongly affect distribution of some trace elements such as Zn speciation in arid and semi-arid soils. Fotovat et al. (1997) reported that the proportion of free hydrated Zn2+ to total Zn ranged from 20-65% at field capacity soil water content and decreased with increases in solution to soil ratios, while the proportion of Zn complexed with organic ligands increased dramatically in soils. However, solution to soil ratios do not strongly affect the distribution of Cu speciation in soil solution since Cu primarily occurs as organic complexes in these soil solutions. 

It will be shown in Section V that in the case of hydrogen-group II acceptor (Be, Zn) complexes, the hydrogen is located in a bond centered (BC) position between the acceptor and one of the group V neighbors (P,... 

The broad PL emission spectra of some metal chelates match the requirements for white emission. Hamada et al. investigated a series of Zn complexes and found bis(2-(2-hydroxy-phenyl)benzothiazolate)zinc (Zb(BTZ)2, 246) is the best white emission candidate. An OLED with a structure of ITO/TPD/Zn(BTZ)2/OXD-7/Mg In showed greenish-white emission with CIE (0.246, 0.363) with a broad emission spectrum (FWHM 157 nm) consisting of two emission peaks centered at 486 and 524 nm (Figure 3.14) [277], A maximum luminance of 10,190 cd/m2 at 8 V was achieved. The electronic and molecular structure of Zn(BTZ)2 have been elucidated by Liu et al. [278]. There is evidence that the dimeric structure [Zn(BTZ)2]2 in the solid state is more stable than its monomer Zn(BTZ)2. They also found that the electron transport property of Zn(BTZ)2 is better than that of Alq3. 

Predicted formation times0 of Cd, Pb, Zn complexes with EDTA 10 6 - 1... 

The syntheses of the receptors 10 and 12 were carried out by the treatment of bisphenol porphyrin 13 and its Zn complex 14, respectively, with portionwise addition of a large excess of P-cyclodextrin-6-O-monotosylate (CD-Tos) 15 using caesium carbonate as base in N,N dimethyl formamide (DMF) (Fig. 6) (13). 

As shown in Table XIV, the stability constant for the meconate complex of UO is much higher than that for the corresponding kojate complex (log ifi(mec) — 11.8, log ifi(koj) = 7.1) (230). This behavior parallels that for the Zn complexes of this pair of ligands (log ifi(mec) = 7.3, log ifi(koj) — 5.0 cf. Section III.A.2 earlier), and in turn refiects a large difference in pAa values for meconic and kojic acids. 

The Ni - and Zn " " -complexes of phenyl and salicyl esters of pyridine-2,6-dicarboxylic acid [50a and b] hydrolyse much faster than the uncomplexed esters (Breslow and McAllister, 1971) the rate of hydroxide ion catalysis of the Ni " -complexes increases 9300... 

Figure 23. Mesoporous silica supported Zn-complex catalysts [91].

Besides olefin epoxidation, C02/epoxide copolymerization reactions were catalyzed with Zn-complex catalyst 10 (Figure 23) [91] as well as a silsesquinoxane-based Zn-complex [92] synthesized via multi-step in situ synthetic strategies. 

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