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1.
New mixed-anion cadmium(II) complexes of 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) ligands, [Cd(phen)2(NO2)1.65(NO3)0.35] and Cd(bpy)(ClO4)(CH3COO) have been synthesized and characterized by elemental analysis, IR-, 1H NMR-, 13C- NMR and 113Cd NMR spectroscopy. The single crystal X-ray data of [Cd(phen)2(NO2)1.65(NO3)0.35] show the complex to be a monomer and that the Cd atom has an unsymmetrical eight-coordinate geometry, being coordinated by four nitrogen atoms of ‘phen’ ligands and four oxygen atoms of the nitrite and nitrate anions. There is a short ππ stacking interaction between parallel aromatic rings.  相似文献   

2.
Two europium trifluoroacetate complexes, Eu(CF3COO)3·phen ( 1 ) and Eu(CF3COO)3·bpy ( 2 ) (where phen=1,10‐phenanthroline, bpy=2,2′‐bipyridine), were synthesized and characterized by elemental analysis, Fourier transform infrared spectroscopy (FT‐IR), photoluminescence (PL) spectroscopy and thermogravimetric analysis (TA). Single‐crystal X‐ray structure has been determined for the complex [Eu2(CF3COO)6·(phen)3·(H2O)2]·EtOH. The crystal structure of [Eu2(CF3COO)6·(phen)3·(H2O)2]·EtOH shows that two different coordination styles with europium ions coexist in the same crystal and have entirely different coordination geometries and numbers. This crystal can be considered as an 1:1 adduct of [Eu(CF3COO)3·(Phen)2·H2O]·EtOH (9‐coordination part) and Eu(CF3COO)3·phen·H2O (8‐coordination part). The excitation spectra of the two complexes demonstrate that the energy collected by "antenna ligands" is transferred to Eu3+ ions efficiently. The room‐temperature PL spectra of the complexes are composed of the typical Eu3+ ions red emission, due to transitions between 5D07FJ(J=0→4). The lifetimes of 5D0 of Eu3+ in the complexes were examined using time‐resolved spectroscopic analysis, and the lifetime values of Eu(CF3COO)3·phen and Eu(CF3COO)3·bpy were fitting with bi‐exponential (2987 and 353 µs) and monoexponential (3191 µs) curves, respectively. In order to elucidate the energy transfer process of the europium complexes, the energy levels of the relevant electronic states had been estimated. The thermal analyses indicate that they are all quite stable to heat.  相似文献   

3.
Two nitrilotriacetate cobalt complexes {[CoK2(NTA)(Hmta)(H2O)3]NO3}n ( 1 ) and [{Co(4,4′‐bpy)2(H2O)4}{Co2(NTA)2(4,4′‐bpy)(H2O)2}] ( 2 ) (NTA = nitrilotriacetate anion, Hmta = hexamethylenetetramine and 4,4′‐bpy = 4,4′‐bipyridine) were prepared and characterized by IR, elemental analysis and single crystal X‐ray diffraction study. The influence of the neutral ancillary ligands on the formation of the complexes with different structures in the Co‐NTA system was discussed. The coordination of NTA and Hmta to Co2+ ions only resulted in the formation of mononuclear [Co(NTA)(Hmta)]? ions which are further connected by K+ ions and water molecules to form a three‐dimensional network. The use of 4,4′‐bpy as ancillary ligand in 2 led to the formation of separate mononuclear [Co(4,4′‐bpy)2(H2O)4]2+ and dinuclear [Co2(NTA)2(4,4′‐bpy)(H2O)2]2? which are further connected by hydrogen bonds to form a supramolecular three‐dimensional network. In these cases it seems to suggest that the addition of neutral ancillary ligand into the Co‐NTA system leads to the formation of lower dimensional structures when the contribution of alkali ions to the structural dimensionality is neglected.  相似文献   

4.
The ligand pteridino[6,7‐f] [1,10]phenanthroline‐11,13‐diamine (ppn) and its RuII complexes [Ru(bpy)2(ppn)]2+ ( 1 ; bpy=2,2′‐bipyridine) and [Ru(phen)2(ppn)]2+ ( 2 ; phen=1,10‐phenanthroline) were synthesized and characterized by elemental analysis, electrospray MS, 1H‐NMR, and cyclic voltammetry. The DNA‐binding behaviors of 1 and 2 were studied by spectroscopic and viscosity measurements. The results indicate that both complexes strongly bind to calf‐thymus DNA in an intercalative mode, with DNA‐binding constants Kb of (1.7±0.4)?106 M ?1 and (2.6±0.2)?106 M ?1, respectively. The complexes 1 and 2 exhibit excellent DNA‐‘light switch’ performances, i.e., they do not (or extremely weakly) show luminescence in aqueous solution at room temperature but are strongly luminescent in the presence of DNA. In particular, the experimental results suggest that the ancillary ligands bpy and phen not only have a significant effect on the DNA‐binding affinities of 1 and 2 but also have a certain effect on their spectral properties. [Ru(phen)2(ppn)]2+( 2 ) might be developed into a very prospective DNA‐‘light switch’ complex. To explain the DNA‐binding and spectral properties of 1 and 2 , theoretical calculations were also carried out applying the DFT/TDDFT method.  相似文献   

5.
The title compound [La(phen)2(H2O)2(NO3)2](NO3) · 2(phen)(H2O) with phen = 1,10‐phenanthroline was prepared by the stoichiometric reaction of La(NO3)3 · 6 H2O and 1,10‐phenanthroline monohydrate in a CH3OH–H2O solution. The crystal structure (triclinic, P 1 (no. 2), a = 11.052(2), b = 13.420(2), c = 16.300(2) Å, α = 78.12(1)°, β = 88.77(1)°, γ = 83.03(1)°, Z = 2, R = 0.0488, wR2 = 0.1028) consists of [La(phen)2(H2O)2(NO3)2]2+ complex cations, NO3 anions, phen and H2O molecules. The La atom is 10‐fold coordinated by four N atoms of two bidentate chelating phen ligands and six O atoms of two H2O molecules and two bidentate chelating NO32– ligands with d(La–O) = 2.522–2.640 Å and d(La–N) = 2.689–2.738 Å. The intermolecular π‐π stacking interactions play an essential role in the formation of two different 2 D layers parallel to (001), which are formed by complex cations and uncoordinating phen molecules, respectively. The uncoordinated NO3 anions and H2O molecules are sandwiched between the cationic and phen layers.  相似文献   

6.
Three new nickel(II) complexes formulated as [Ni2(1,3‐tpbd)(diimine)2(H2O)2]4+ [1,3‐tpbd = N,N,N′,N′‐tetrakis(2‐pyridylmethyl)benzene‐1,3‐diamine, where diimine is an N,N‐donor heterocyclic base like 1,10‐phenanthroline (phen),2,2′‐bipyridine (bpy), 4,5‐diazafluoren‐9‐one (dafo)], have been synthesized and structurally characterized by X‐ray crystallography: [Ni2(1,3‐tpbd)(phen)2(H2O)2]4+ (1), [Ni2(1,3‐tpbd)(bpy)2(H2O)2]4+(2) and [Ni2(1,3‐tpbd)(dafo)2(H2O)2]4+ (3). Single‐crystal diffraction reveals that the metal atoms in the complexes are all in a distorted octahedral geometry and in a trans arrangement around 1,3‐tpbd ligand. The interactions of the three complexes with calf thymus DNA (CT‐DNA) have been investigated by UV absorption, fluorescence spectroscopy, circular dichroism and viscosity. The apparent binding constant (Kapp) values are calculated to be 1.91 × 105 m ?1 for 1, 1.18 × 105 m ?1 for 2, and 1.35 × 105 m ?1 for 3, following the order 1 > 3 > 2. The higher DNA binding affinity of 1 is due to the involvement in partial insertion of the phen ring between the DNA base pairs. A decrease in relative viscosities of DNA upon binding to 1–3 is consistent with the DNA binding affinities. These complexes efficiently display oxidative cleavage of supercoiled DNA in the presence of H2O2 (250 µ m ), with 3 exhibiting the highest nuclease activity. The rate constants for the conversion of supercoiled to nicked DNA are 5.28 × 10?5 s?1 (for 1), 6.67 × 10?5 s?1 (for 2) and 1.39 × 10?4 s?1 (for 3), also indicating that complex 3 shows higher catalytic activity than 1 and 2. Here the nuclease activity is not readily correlated to binding affinity. The inhibitory effect of complexes 1–3 on thioredoxin reductase has also been examined. The IC50 values are calculated to be 26.54 ± 0.57, 31.03 ± 3.33 and 8.69 ± 2.54 µ m , respectively, showing a more marked inhibitory effect on thioredoxin reductase by complex 3 than the other two complexes. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

7.
Novel EuIII complexes with bidentate phosphine oxide ligands containing a bipyridine framework, i.e., [3,3′‐bis(diphenylphosphoryl)‐2,2′‐bipyridine]tris(hexafluoroacetylacetonato)europium(III) ([Eu(hfa)3(BIPYPO)]) and [3,3′‐bis(diphenylphosphoryl)‐6,6′‐dimethyl‐2,2′‐bipyridine]tris(hexafluoroacetylacetonato)europium(III) ([Eu(hfa)3(Me‐BIPYPO)]), were synthesized for lanthanide‐based sensor materials having high emission quantum yields and effective chemosensing properties. The emission quantum yields of [Eu(hfa)3(BIPYPO)] and [Eu(hfa)3(Me‐BIPYPO)] were 71 and 73%, respectively. Metal‐ion sensing properties of the EuIII complexes were also studied by measuring the emission spectra of EuIII complexes in the presence of ZnII or CuII ions. The metal‐ion sensing and the photophysical properties of luminescent EuIII complexes with a bidentate phosphine oxide containing 2,2′‐bipyridine framework are demonstrated for the first time.  相似文献   

8.
Seven new transition metal complexes formulated as [M2(1,4-tpbd)(diimine)2(H2O)2]4+ [M = Zn, Co, Ni, Cd; 1,4-tpbd = N,N,N′,N′-tetrakis(2-pyridylmethyl)benzene-1,4-diamine; diimine is a N,N-donor heterocyclic base like 1,10-phenanthroline (phen), 2,2′-bipyridine (bpy), 4,5-diazafluoren-9-one (dafo)] have been synthesized and structurally characterized by X-ray crystallography: [Zn2(1,4-tpbd)(phen)2(H2O)2]4+ (1), [Zn2(1,4-tpbd)(bpy)2(H2O)2]4+ (2), [Co2(1,4-tpbd)(phen)2(H2O)2]4+ (3), [Ni2(1,4-tpbd)(phen)2(H2O)2]4+ (4), [Ni2(1,4-tpbd)(bpy)2(H2O)2]4+ (5), [Ni2(1,4-tpbd)(dafo)2(H2O)2]4+ (6) and [Cd2(1,4-tpbd)(phen)2(H2O)2]4+ (7). Single crystal diffraction reveals that the metals in the complexes are all in a distorted octahedral geometry. The interactions of the seven complexes with calf thymus DNA (CT-DNA) have been investigated by UV absorption, fluorescence, circular dichroism spectroscopy and viscosity measurements. The apparent binding constants (Kapp) are calculated to be 5.2?×?105 M?1 for 1, 1.05?×?105 M?1 for 2, 5.76?×?105 M?1 for 3, 4.57?×?105 M?1 for 4, 1.29?×?105 M?1 for 5, 1.7?×?105 M?1 for 6, 2.53?×?105 M?1 for 7, the binding propensity to the calf thymus DNA in the order: 3 (Co-phen) > 1 (Zn-phen) > 4 (Ni-phen) > 7 (Cd-phen) > 6 (Ni-dafo) > 5 (Ni-bpy) > 2 (Zn-bpy). Furthermore, these complexes display efficient oxidative cleavage of supercoiled DNA; the Zn(II)/H2O2 and Cd(II)/H2O2 systems efficiently cleave DNA attributed to the peroxide ion coordinated to the Zn(II) and Cd(II), which enhanced their nucleophilicity, this is rare.  相似文献   

9.
Two new lead(II) complexes containing nitrite, [Pb(L)2(NO2)2], L?=?1,10-phenanthroline (phen) or 2,2′-bipyridine (bpy), have been synthesized and characterized. The crystal structure of [Pb(phen)2(NO2)2] shows monomeric units. The coordination number is eight (four from “phen” ligands and four nitrite anions), weak interaction of lead(II) with oxygen atoms of adjacent molecules produce dimer units in the solid state. The arrangement of ligands exhibits a coordination hole around the lead(II), occupied possibly by a stereoactive lone pair of electrons on lead(II), and the coordination around lead is hemidirected. There is a π–π stacking interaction between the parallel aromatic rings that may help to increase the “gap” around lead(II).  相似文献   

10.
Three isostructural metal–organic frameworks ([Ln2(phen)2(NO3)2(chdc)2]·2DMF (Ln3+ = Y3+ for 1, Eu3+ for 2 or Tb3+ for 3; phen = 1,10-phenanthroline; H2chdc = trans-1,4-cyclohexanedicarboxylic acid) were synthesized and characterized. The compounds are based on a binuclear block {M2(phen)2(NO3)2(OOCR)4} assembled into a two-dime nsional square-grid network containing tetragonal channels with 26% total solvent-accessible volume. Yttrium (1)-, europium (2)- and terbium (3)-based structures emit in the blue, red and green regions, respectively, representing the basic colors of the standard RGB matrix. A doping of Eu3+ and/or Tb3+ centers into the Y3+-based phase led to mixed-metal compositions with tunable emission color and high quantum yields (QY) up to 84%. The bright luminescence of a suspension of microcrystalline 3 in DMF (QY = 78%) is effectively quenched by diluted cinnamaldehyde (cinnamal) solutions at millimolar concentrations, suggesting a convenient and analytically viable sensing method for this important chemical.  相似文献   

11.
Six new μ-phthalato binuclear oxovanadium(IV) complexes, namely [(VO)2(PHTH)-(L)2]SO4 (L denotes 2,2′-bipyridine (bpy); 1,10-phenanthroline (phen); 4,4′-dimethyl-2,2′-bipyridine (Me2 bpy); 5-nitro-1,10-phenanthroline (NO2-phen); 5-chloro-1,10-phenanthroline (Cl-phen) and 5-methyl-1,10-phenanthroline (CH3-phen), where PHTH is the phthalate dianion), have been synthesized and characterized by elemental analyses, IR, electronic spectra, magnetic moments at room temperature and molar conductivity measurements. The temperature dependence of the magnetic susceptibility of complexes [(VO)2(PHTH)(phen)2]SO4 (1) and [(VO)2(PHTH)(CH3-phen)2]SO4 (2) was measured in 4—300 K range and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, ?=?2J?1·?2, giving the exchange integrals J=?12.8 cm?1 for 1 and J=?7.9 cm?l for 2. This indicates an antiferromagnetic spin-exchange interaction between the metal ions within each molecule.  相似文献   

12.
Reactions of aquapentachloroplatinic acid, (H3O)[PtCl5(H2O)]·2(18C6)·6H2O ( 1 ) (18C6 = 18‐crown‐6), and H2[PtCl6]·6H2O ( 2 ) with heterocyclic N, N donors (2, 2′‐bipyridine, bpy; 4, 4′‐di‐tert‐butyl‐2, 2′‐bipyridine, tBu2bpy; 1, 10‐phenanthroline, phen; 4, 7‐diphenyl‐1, 10‐phenanthroline, Ph2phen; 2, 2′‐bipyrimidine, bpym) afforded with ligand substitution platinum(IV) complexes [PtCl4(N∩N)] (N∩N = bpy, 3a ; tBu2bpy, 3b ; Ph2phen, 5 ; bpym, 7 ) and/or with protonation of N, N donor yielding (R2phenH)2[PtCl6] (R = H, 4a ; Ph, 4b ) and (bpymH)+ ( 8 ). With UV irradiation Ph2phen and bpym reacted with reduction yielding platinum(II) complexes [PtCl2(N∩N)] (N∩N = Ph2phen, 6 ; bpym, 9 ). Identities of all complexes were established by microanalysis as well as by NMR (1H, 13C, 195Pt) and IR spectroscopic investigations. Molecular structures of [PtCl4(bpym)]·MeOH ( 7 ) and [PtCl2(Ph2phen)] ( 6 ) were determined by X‐ray diffraction analyses. Differences in reactivity of bpy/bpym and phen ligands are discussed in terms of calculated structures of complexes [PtCl5(N∩N)] with monodentately bound N, N ligands (N∩N = bpy, 10a ; phen, 10b ; bpym, 10c ).  相似文献   

13.
Three new supramolecular compounds were synthesized and characterized with the formula of [Zn4(picO)4(phen)4]·11.25H2O ( 1 ), [Zn4(picO)4(2,2′‐bpy)4(H2O)4]·12H2O ( 2 ), and [Zn3(picO)3(bpe)5(H2O)3]n·8.5nH2O ( 3 ) (H2picO = 6‐hydroxypicolinic acid; phen = 1,10‐phenanthroline; 2,2′‐bpy = 2,2′‐bipyridine; bpe = 1,2‐bis(4‐pyridyl)ethane). For complexes 1 and 2 , picO ligands adopt tridentate, tetradentate and bidentate coordination modes to link zinc(II) ions into dimers, which are extended into 3D supramolecular structures through hydrogen bonds. Water chains with cyclic page‐like octamer and boat‐like heptamer water clusters are included, respectively. Complex 3 is of a 2D brick‐wall structure. Triple interpenetration occurs, and there are still cyclic chair‐like octamer water clusters in the channels. The fluorescent properties of complexes 1‐3 have also been investigated.  相似文献   

14.
Four μ- oxamido heterodinuclear complexes, [Cu (oxae) Cr (L)2 ] (NO3) 3, where oxae denotes the N, N'bis (2-aminoethyl) oxamido dianion and L represents 1,10-phenanthroline (phen); 5-nitro-1,10-phenanthroline (NO2-phen); 5-methyl-1, 10-phenanthroline (Me-phen) and 2, 2′-bipyridine (bpy), have been synthesized and characterized by elemental analyses, magnetic moments (at room temperature) and molar conductivity measurements and spectroscopy. It is proposed that these complexes have extended oxamido-bridged structures consisting of a copper (II) ion and a chromium (III) ion, which have a square planar environment and octahedral environment, respectively. The cryomagnetic properties of the [Cu(oxae)Cr(bpy)2(NO3)3(1) and [Cu(oxae)Cr(phen)2](NO3)3(2) complexes have been measured over the range of 4.2–300 K. The leastsquares fit of the experimental data based on the spin Hamiltonian, ? = - 2J?1·?2, the exchange integrals (J) were evaluated as +36.9 cm?1 for 1 and +35.8 cm?1 for 2. The reds have connived that the spin coupling between the adjacent copper (II) and chromium (III) ions through oxamido-bridge in both 1 and 2 is ferromagnetic.  相似文献   

15.
Complexation of 1,4‐phenylenebis(methylene) diisonicotinate, L1 , with cis‐protected PdII components, [Pd( L′ )(NO3)2], in an equimolar ratio yielded binuclear complexes, 1 a – d of [Pd2( L′ )2( L1 )2](NO3)4 formulation where L′ stands for ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2′‐bipyridine (bpy), and phenanthroline (phen). The combination of 4,4′‐bipyridine, L2 , with the cis‐protected PdII units is known to yield molecular squares, 2 a – d . However, 2 b – d coexist with the corresponding molecular triangles, 3 b – d . Combination of an equivalent each of the ligands L1 and L2 with two equivalents of cis‐protected PdII components in DMSO resulted in the D ‐shaped heteroligated complexes [Pd2( L′ )2( L1 )( L2 )](NO3)4, 4 a – d . Two units of the D ‐shaped complexes interlock, in a concentration dependent fashion, to form the corresponding [2]catenanes [Pd2( L′ )2( L1 )( L2 )]2(NO3)8, 5 a – d under aqueous conditions. Crystal structures of the macrocycle [Pd2(tmeda)2( L1 )( L2 )](PF6)4, 4 b′′ , and the catenane [Pd2(bpy)2( L1 )( L2 )]2(NO3)8, 5 c , provide unequivocal support for the proposed molecular architectures.  相似文献   

16.
To explore the coordination possibilities of anthracene‐based ligands, three cadmium(ιι) complexes with anthracene‐9‐carboxylate ( L ) and relevant auxiliary chelating or bridging ligands were synthesized and characterized: Cd2( L )4(2bpy)2(μ‐H2O) ( 1 ), Cd2( L )4(phen)2(μ‐H2O) ( 2 ), and {[Cd3( L )6(4bpy)]} ( 3 ) (2bpy = 2,2′‐bipyridine, phen = 1,10‐phenanthroline, and 4bpy = 4,4′‐bipyridine). Structural analyses show that complexes 1 and 2 both take dinuclear structures by incorporating the chelating 2bpy or phen ligand, which are further interlinked by intermolecular hydrogen‐bonding, π ··· π stacking, and/or C–H ··· π supramolecular interactions to generate higher‐dimensional supramolecular frameworks. Complex 3 has a one‐dimensional (1D) ribbon‐like structure, which is further assembled into a two‐dimensional (2D) layer, and a three‐dimensional (3D) framework by the co‐effects of interchain C–H ··· O hydrogen‐bonding and C–H ··· π supramolecular interactions. Moreover, the luminescent properties of these complexes were further investigated in detail.  相似文献   

17.
The 1:2 adduct lead(II) complexes with 1, 10‐phenanthroline (phen) containing three different anions, [Pb(phen)2(CH3COO)X] (X=NCS, NO3 and ClO4), have been synthesized and characterized by CHN elemental analysis, IR‐, 1H‐ and 13C NMR spectroscopy. The structure of [Pb(phen)2(CH3COO)(ClO4)] was determined by single crystal X‐ray analysis. The Pb atom of the monomeric complex is coordinated by four nitrogen atoms of two 1, 10‐phenanthroline ligands and two oxygen atoms of the acetate ligand to form an irregular octahedron. The arrangement of the 1, 10‐phenanthroline and acetate ligands, exhibits a coordination gap around the PbII ion, possibly occupied by a stereochemical electron active lone pair on lead(II), which results in a hemidirected lead compound. The π‐π stacking interaction between the parallel aromatic rings may help to increase the coordination ‘gap’ around the PbII ion.  相似文献   

18.
DFT methods were utilized to study SCO complexes. [Fe(2btz)2(NCX)2] (2btz = 2,2′‐bithiazoline, X = S ( 1 ) and Se ( 2 )), [Fe(phen)2(NCX)2] (phen = 1,10‐phenantroline, X = S ( 3 ) and Se ( 4 )), and [Fe(bpy)2(NCS)2] ( 5 ) (bpy = 2,2′‐bipyridine) compounds, which have experimentally shown SCO behavior, were calculated. B3LYP, B3LYP*, OPBE, and OLYP with 6‐31G* and 6‐311 + G** basis sets were employed to calculate the ΔEHS/LS energy gap as a clue to find complexes with SCO behavior. It is found that calculated result by B3LYP* with c3 = 0.14 and OPBE methods and 6‐31G* basis set are in agreement with experimentally observed SCO complexes. Then, newly designed Fe(N‐N)2(X)2 complexes, where N‐N are bidentate nitrogen donor chelating ligands and X= SCN, SeCN, Cl, Br, I, were chosen to see their potential to be SCO compounds. ΔEHS/LS for potential SCO complexes are estimated from 0.8 to 6.5 kcal/mol in B3LYP* and 0.6–5.7 kcal/mol in OPBE. These calculations suggest [Fe(bpy)2(NCSe)2], [Fe(5dmbpy)2(NCS)2], and [Fe(3‐BrPhen)2(NCSe)2] compounds have the ability to show SCO behavior. © 2016 Wiley Periodicals, Inc.  相似文献   

19.
Two new complexes [Zn2(phen)4(FCA)2](ClO4)2·(H2O)2 ( 1 ) and [Co2(phen)4 (FCA)2](ClO4)2·(H2O)2 (2) (FCA=anion of 3‐ferrocenyl‐2‐crotonic acid, phen=1,10‐phenanthroline) have been synthesized, and characterized by elemental analysis, IR, UV‐Vis spectra, thermal analyses, and single‐crystal X‐ray diffraction. Two M(II) (M=Zn or Co) ions are bridged by two FCA anions with syn‐anti bridging ligands, leading to dimeric cores, [M2(phen)4(FCA)2]2+, and each M(II) ion is six‐coordinated in a distorted octahedral geometry by two chelate phen ligands and two μ2‐carboxylate oxygen atoms from two FCA groups. The M(II)…M(II) intradimer distances are 0.4391 and 0.4462 nm in 1 and 2 , respectively. Electrochemical properties of the complexes have been discussed.  相似文献   

20.
To study the conversion from a meso form to a racemic form of tetrahydrofurantetracarboxylic acid (H4L), seven novel coordination polymers were synthesized by the hydrothermal reaction of Zn(NO3)2 ? 6 H2O with (2S,3S,4R,5R)‐H4L in the presence of 1,10‐phenanthroline (phen), 2,2′‐bipyridine (2,2′‐bpy), or 4,4′‐bipyridine (4,4′‐bpy): [Zn2{(2S,3S,4R,5R)‐L}(phen)2(H2O)] ? 2 H2O ( 1 ), [Zn4{(2S,3R,4R,5R)‐L}{(2S,3S,4S,5R)‐L}(phen)2(H2O)2] ( 2 ), [Zn2{(2S,3S,4R,5R)‐L}(H2O)2] ? H2O ( 3 ), [Zn4{(2S,3R,4R,5R)‐L}{(2S,3S,4S,5R)‐L} (2,2′‐bpy)2(H2O)2] ? 2 H2O ( 4 ), [Zn2 {(2S,3S,4R,5R)‐L}(2,2′‐bpy)(H2O)] ( 5 ), [Zn4{(2S,3R,4R,5R)‐L}{(2S,3S,4S,5R)‐L} (4,4′‐bpy)2(H2O)2] ( 6 ), and [Zn2 {(2S,3S,4R,5R)‐L}(4,4′‐bpy)(H2O)] ? 2 H2O ( 7 ). These complexes were obtained by control of the pH values of reaction mixtures, with an initial of pH 2.0 for 1 , 2.5 for 2 , 4 , and 6 , and 4.5 for 3 , 5 , and 7 , respectively. The expected configuration conversion has been successfully realized during the formation of 2 , 4 , and 6 , and the enantiomers of L, (2S,3R,4R,5R)‐L and (2S,3S,4S,5R)‐L, are trapped in them, whereas L ligands in the other four complexes retain the original meso form, which indicates that such a conversion is possibly pH controlled. Acid‐catalyzed enol–keto tautomerism has been introduced to explain the mechanism of this conversion. Complex 1 features a simple 1D metal–L chain that is extended into a 3D supramolecular structure by π–π packing interactions between phen ligands and hydrogen bonds. Complex 2 has 2D racemic layers that consist of centrosymmetric bimetallic units, and a final 3D supramolecular framework is formed by the interlinking of these layers through π–π packing interactions of phen. Complex 3 is a 3D metal–organic framework (MOF) involving meso‐L ligands, which can be regarded as (4,6)‐connected nets with vertex symbol (45.6)(47.68). Complexes 4 and 5 contain 2D racemic layers and (6,3)‐honeycomb layers, respectively, both of which are combined into 3D supramolecular structures through π–π packing interactions of 2,2′‐bpy. The structure of complex 6 is a 2D network formed by 4,4′‐bpy bridging 1D tubes, which consist of metal atoms and enantiomers of L. These layers are connected through hydrogen bonds to give the final 3D porous supramolecular framework of 6 . Complex 7 is a 3D MOF with novel (3,4,5)‐connected (63)(42.64)(42.66.82) topology. The thermal stability of these compounds was also investigated.  相似文献   

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