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1.
Bazzicalupi C Bencini A Berni E Bianchi A Ciattini S Giorgi C Maoggi S Paoletti P Valtancoli B 《The Journal of organic chemistry》2002,67(25):9107-9110
The synthesis of three new tris-macrocycles, containing three [12]aneN(4) (L1), [12]aneN(3)O (L2), or [14]aneN(4) (L3) moieties appended to a tren unit, is reported. The crystal structure of the [(Na(ClO(4))(6)) subset L1(2)H(13)]Na(6)Cl(2)(ClO(4))(12) compound shows the anionic cluster [Na(ClO(4))(6)](5)(-) assembled inside the cavity defined by two bowl-shaped polyammonium receptors, held by multiple charge-charge and hydrogen bond interactions. 相似文献
2.
Bazzicalupi C Bencini A Berni E Bianchi A Fornasari P Giorgi C Valtancoli B 《Inorganic chemistry》2004,43(20):6255-6265
Zn(II) binding by the dipyridine-containing macrocycles L1-L3 has been analyzed by means of potentiometric measurements in aqueous solutions. These ligands contain one (L1, L2) or two (L3) 2,2'-dipyridine units as an integral part of a polyamine macrocyclic framework having different dimensions and numbers of nitrogen donors. Depending on the number of donors, L1-L3 can form stable mono- and/or dinuclear Zn(II) complexes in a wide pH range. Facile deprotonation of Zn(II)-coordinated water molecules gives mono- and dihydroxo-complexes from neutral to alkaline pH values. The ability of these complexes as nucleophilic agents in hydrolytic processes has been tested by using bis(p-nitrophenyl) phosphate (BNPP) as a substrate. In the dinuclear complexes the two metals play a cooperative role in BNPP cleavage. In the case of the L2 dinuclear complex [Zn(2)L2(OH)(2)](2+), the two metals act cooperatively through a hydrolytic process involving a bridging interaction of the substrate with the two Zn(II) ions and a simultaneous nucleophilic attack of a Zn-OH function at phosphorus; in the case of the dizinc complex with the largest macrocycle L3, only the monohydroxo complex [Zn(2)L3(OH)](3+) promotes BNPP hydrolysis. BNPP interacts with a single metal, while the hydroxide anion may operate a nucleophilic attack. Both complexes display high rate enhancements in BNPP cleavage with respect to previously reported dizinc complexes, due to hydrophobic and pi-stacking interactions between the nitrophenyl groups of BNPP and the dipyridine units of the complexes. 相似文献
3.
Paolo Dapporto Paola Paoli Carla Bazzicalupi Andrea Bencini Nicoletta Nardi Barbara Valtancoli 《Supramolecular chemistry》2013,25(3):195-200
Abstract In preceding works, which have dealt with the synthesis and characterisation of a series of macrobicyclic compounds with five donor atoms, the unusually high basicity constants of these polyaminic cage-like molecules have been ascribed to the inclusion of the proton inside the macrobicyclic cavity which results in a very efficient hydrogen-bond network. The present paper, based on previously reported X-ray crystal structures regarding five-atoms bridging units and on molecular modelling studies shows that the disposition of the five donor atoms in the monoprotonated species is related to the protonation site. Precisely, if the protonation occurs on a bridge-head nitrogen the resulting geometry of the donors is a trigonal bipyramid, whereas it is square pyramidal when the proton is bound to a nitrogen belonging to a macrobicyclic chain. For what concerns the geometrical array of the donor atoms in the free amines, the favoured array seems to be the trigonal bipyramidal. 相似文献
4.
Mascaros PA Bazzicalupi C Bianchi A Giorgi C Valero MD Garzón RL Salido ML Valtancoli B 《Chemical communications (Cambridge, England)》2011,47(10):2814-2816
The synergistic action of the different binding groups of the polyfunctional HL receptor leads to the recognition of ADP over ATP in water, with a selectivity coefficient of up to 116, a phenomenon which is unprecedented in the context of synthetic receptors in water. The recognition is mostly due to the good matching between H(3)L(2+) and the protonated forms of ADP. 相似文献
5.
Bazzicalupi C Bencini A Bianchi A Borri C Danesi A Garcia-España E Giorgi C Valtancoli B 《The Journal of organic chemistry》2008,73(21):8286-8295
The interaction of the biologically relevant anions deriving from the six pyridinedicarboxylic acids (H2PDC) with two macrocyclic receptors containing a pentamine chain and a bipyridine (1) or a phenanthroline (2) moiety, as well as with the aliphatic analogue [21]aneN7 (3), was studied by means of spectroscopic methods (UV-vis, NMR) and potentiometric titrations affording the stability constants of the adducts formed. All three receptors form stable complexes with the substrates thanks to the formation of several salt bridges and hydrogen bond contacts, as observed in the crystal structure of the H8[3(2,6-PDC)4] x H2O x 0.5 EtOH solid compound. Additional pi-stacking interactions between the aromatic moieties of substrates and receptors enhance the stability of complexes with 1 and 2. Compounds 1 and 2 show a marked selectivity toward 2,6-pyridinedicarboxylate anions. In particular, 1 is able to perform a very efficient recognition of these species in the presence of 2 and 3. Molecular modeling calculations suggested that such recognition ability of 1 can be ascribed to a superior structural and electrostatic complementarity with the substrate compared to 2 and 3. 相似文献
6.
Bazzicalupi C Bencini A Bianchi A Faggi E Giorgi C Santarelli S Valtancoli B 《Journal of the American Chemical Society》2008,130(8):2440-2441
7.
Bazzicalupi C Bencini A Bussotti L Berni E Biagini S Faggi E Foggi P Giorgi C Lapini A Marcelli A Valtancoli B 《Chemical communications (Cambridge, England)》2007,(12):1230-1232
A dizinc complex with a polyamine macrocycle is able to selectively bind and sense uridine (U) as well as the uridine-containing ribodinucleotides U(3'-5')pU and U(3'-5')pA, thanks to an exciplex emission arising from a pi-stacked complex involving the dipyridine unit and Zn(II)-bound uridine moieties. 相似文献
8.
Carla Bazzicalupi Antonio Bianchi Claudia Giorgi M. Paz Clares Enrique García-España 《Coordination chemistry reviews》2012,256(1-2):13-27
Chemical systems, in particular those involving biological and environmental backgrounds, develop through selective processes which are determined by multiple equilibria. Several methods that have been developed to assess thermodynamic selectivity in binding equilibria, including the analysis of selectivity coefficients, the use of calculated species distribution diagrams, selectivity diagrams, and conditional stability constants, are reviewed in this paper with reference to examples mainly related to chemical systems of biological and/or environmental concern. Also the concept of binding affinity has been dealt with, since binding selectivity in equilibrium systems relates to the different affinities with which chemical species bind to each other. 相似文献
9.
Bazzicalupi C Bencini A Bencini A Bianchi A Corana F Fusi V Giorgi C Paoli P Paoletti P Valtancoli B Zanchini C 《Inorganic chemistry》1996,35(19):5540-5548
Solutions containing Zn(II) and Cu(II) complexes with [15]aneN(3)O(2) rapidly adsorb atmospheric CO(2) to give {[ZnL](3)(&mgr;(3)-CO(3))}.(ClO(4))(4) (2) and {[CuL](3)(&mgr;(3)-CO(3))}.(ClO(4))(4) (4) complexes. The crystal structures of both complexes have been solved (for 2, space group R3c, a, b = 22.300(5) ?, c = 17.980(8) ?, V = 7743(4) ?(3), Z = 6, R = 0.0666, R(w)(2) = 0.1719; for 4, space group R3c, a, b = 22.292(7) ?, c = 10.096(8) ?, V = 7788(5) ?(3), Z = 6, R = 0.0598, R(w)(2) = 0.1611), and the spectromagnetic behavior of 4 has been studied. In both compounds a carbonate anion triply bridges three metal cations. Each metal is coordinated by one oxygen of the carbonate, three nitrogens, and an oxygen of the macrocycle; the latter donor weakly interacts with the metals. Although the two compounds are isomorphous, they are not isostructural, because the coordination geometries of Zn(II) in 2 and Cu(II) in 4 are different. The mixed complex {[CuZn(2)L(3)](&mgr;(3)-CO(3))}.(ClO(4))(4) has been synthesized. X-ray analysis (space group R3c, a, b = 22.323(7) ?, c = 17.989(9) ?, V = 7763(5) ?(3), Z = 6, R = 0.0477, R(w)(2) = 0.1371) and EPR measurements are in accord with a &mgr;(3)-carbonate bridging one Cu(II) and two Zn(II) ions in {[CuZn(2)L(3)](&mgr;(3)-CO(3))}(4+). Both the Zn(II) and Cu(II) cations exhibit the same coordination sphere, almost equal to that found in the trinuclear Zn(II) complex 2. The systems Zn(II)/L and Cu(II)/Lhave been studied by means of potentiometric measurements in 0.15 mol dm(-)(1) NaCl and in 0.1 mol dm(-)(3) NaClO(4) aqueous solutions; the species present in solution and their stability constants have been determined. In both systems [ML](2+) species and hydroxo complexes [M(II)LOH](+) (M = Zn, Cu) are present in solution. In the case of Cu(II), a [CuL(OH)(2)] complex is also found. The process of CO(2) fixation is due to the presence of such hydroxo-species, which can act as nucleophiles toward CO(2). In order to test the nucleophilic ability of the Zn(II) complexes, the kinetics of the promoted hydrolysis of p-nitrophenyl acetate has been studied. The [ZnLOH](+) complex promotes such a reaction, where the Zn(II)-bound OH(-) acts as a nucleophile to the carbonyl carbon. The equilibrium constants for the addition of HCO(3)(-) and CO(3)(2)(-) to the [ZnL](2+) complex have been potentiometrically determined. Only [ML(HCO(3))](+) and [ML(CO(3))] species are found in aqueous solution. A mechanism for the formation of {[ML](3)(&mgr;(3)-CO(3))}.(ClO(4))(4) is suggested. 相似文献
10.
The presence of intramolecular CH... aromatic bonds in organic molecules has been analyzed by means of CSD searches. In particular, molecules containing aromatic and methyl groups have been examined as a function of the length of the chain separating the interacting groups. The type of bonds in the chain and its geometry have also been taken into account. The maximum number of CH... interactions have been found for five-membered chains joining the aromatic and methyl moieties. In addition, this interaction seems favored when the chain contains two sp
2 hybridized atoms. The interactions involving polypeptides have been carefully examined. Interest has focused on compounds containing both aromatic and methylic residues, i.e., a combination of phenylalanine (phe), tyrosine (tyr), and tryptophan (trp) with alanine (ala), valine (val), leucine (leu), and isoleucine (ile). The maximum number of CH... interactions have been found when five atoms constituted the chain, i.e., in the sequences phe–ala and ala–phe. 相似文献