N. V. Gogoleva

Cell-to-cell communication in the populations of enterobacterium Erwinia carotovora ssp. atroseptica SCRI1043 during adaptation to stress conditions

Erwinia carotovora ssp. atroseptica SCRI1043 is a plant pathogenic bacterium. Many species of enterobacteria including Erwinia sp. can induce the onset or the progression of opportunistic or persistent infections in humans. The existence of these bacteria within different ecological niches is related to their significant adaptive potential. The triggering of adaptive reactions, which are needed for bacterial persistence, is controlled in many cases by intercellular communication; hence, the ability to survive under unfavourable conditions is regulated in a cell-density-dependent manner. In this study, we showed that, during starvation of E. carotovora ssp. atroseptica SCRI1043, the initial stage of the response to stress was stabilization of the density of culturable cells in the range 10(6)-10(7) CFU mL(-1). The number of culturable cells increased (up to approximately 10(6) CFU mL(-1)) when cultures were inoculated at a low cell density (10(3)-10(5) CFU mL(-1)), and at the same time, acylhomoserine lactone (AHL)-dependent quorum sensing was activated. Our results showed that the regulation of cell density in starving populations of E. carotovora ssp. atroseptica SCRI1043 occurred and this regulation was carried out with the involvement of the cell-to-cell communication.

Dissociation of a population of Pectobacterium atrosepticum SCRI1043 in tobacco plants: formation of bacterial emboli and dormant cells

The population dynamics of Pectobacterium atrosepticum SCRI1043 (Pba) within tobacco plants was monitored from the time of inoculation until after long-term preservation of microorganisms in the remnants of dead plants. We found and characterised peculiar structures that totally occlude xylem vessels, which we have named bacterial emboli. Viable but non-culturable (VBN) Pba cells were identified in the remnants of dead plants, and the conditions for resuscitation of these VBN cells were established. Our investigation shows that dissociation of the integrated bacterial population during plant colonisation forms distinct subpopulations and cell morphotypes, which are likely to perform specific functions that ensure successful completion of the life cycle within the plant.

2D coordination polymers of AgI—MII (MII = Ni, Cu) with anions of substituted malonic acids

Heterometallic malonate complexes [Ag2Ni(H2O)2(R2mal)2]n (R2mal2– is the dimethylmalonate dianion (Me2mal2–) (1) or the cyclobutane-1,1-dicarboxylate dianion (Cbdc2–) (2)) and [Ag2Cu(H2O)(Me2mal)2]n (3) were synthesized. The bis-chelate fragment {M(R2mal)2} (M = Ni, Cu) composed of two dianions of an acid and a 3d metal atom is the structure-forming unit of these complexes. The mononuclear fragments are linked by silver(I) atoms, which are involved in argentophilic interactions, to form 2D coordination polymers.

36-Nuclear CoII and NiII dimethylmalonate complexes with the [K(18-crown-6)]+ cationic fragments: synthesis and structure

A reaction of potassium dimethylmalonate (K2Me2Mal) with cobalt(II) or nickel(II) trimethylacetate in the presence of 18-crown-6 leads to the formation of 36-nuclear complexes {[K(18-crown-6)]2[K(H2O)(18-crown-6)]2[K6Co36(H2O)20(OH)18(Me2Mal)30(18-crown6)2(O)2]•xH2O}n (2) and {[K(H2O)2(18-crown-6)]6[K5Ni36(H2O)20(OH)18(18-crown-6)2(Me2Mal)28(HMe2Mal)2]4[K5Ni36(H2O)20(OH)20(18-crown-6)2(Me2Mal)29(HMe2Mal)]• •80H2O}n (3) (Me2Mal2– is the dianion of dimethylmalonic acid), respectively. The single crystal X-ray diffraction studies showed that the spherical 36-nuclear polyanions [Co36(H2O)12(OH)18(Me2Mal)30(O)2]10– (in compound 2) and [Ni36(H2O)12(OH)20(Me2Mal)30–x(HMe2Mal)x]y– (in compound 3; x = 1, y = 7; x = 2, y = 6) have similar structures, with their metal cores being formed of two layers: an internal one comprising 24 metal atoms and an external containing 12 metal centers. The inner cavity of the {MII36} anions was found to include one K+ aqua cation bonded to the oxygen atoms of the carboxylate or oxo ligands.

Erratum to: “The formation of heterometallic molecular architectures with 3d-metal atoms linked by carboxylate bridges with alkali and alkaline-earth metal ions or with lanthanides”

Data on the synthesis of carboxylate complexes combining transition 3d metals and diverse heterometals (Li-, Mg-, and Ln-M(3d)) are reviewed. The factors that are essential to the structure of heterometallic complexes were revealed. Stable metal-containing moieties capable of forming both molecular and polymeric structures were identified.

Influence of geometric and electronic features of pyridine derivatives and triethylamine on the formation of a metal carboxylate core in reactions producing cadmium(ii) pivalate complexes

The reaction products of [Cd(piv)2] (piv is–O2CBut) with isoquinoline (iqn), 2,4-lutidine (lut), phenanthridine (phend), 2,3-cyclododecenopyridine (cpy), and triethylamine (Et3N) were synthesized and their structures were determined. The steric factors were found to play a more important role in cadmium(ii) pivalate complexes compared to 3d metal carboxylates in the +2 oxidation state. The reaction of [Cd(piv)2] with isoquinoline produces only the mononuclear complex [Cd(piv)2(iqn)3] (1). The reaction of [Cd(piv)2] with pyridine derivatives bearing a bulky substituent at the α position is accompanied by the formation of symmetrical dinuclear complexes of the composition [Cd2(piv)4(L)2]. In the complexes with L = lut (2) or phend (3), the cadmium(ii) atoms are linked by two chelating-bridging carboxylate groups; in the complex with L = cpy (4), by four bidentate-bridging groups. The reaction of [Cd(piv)2] with Et3N in a solution of MeCN gives the centrosymmetric linear trinuclear complex [Cd3(piv)6(Et3N)2] (6); in a mixture of benzene and hexane, the ionic compound (HEt3N)[Cd2(piv)5(H2O)] (7). The crystal structures of all synthesized compounds were determined by X-ray diffraction.

Structures and magnetic properties of new trinuclear CoII, NiII, and CuII complexes with trimethylacetate and 1,1-cyclohexanediacetate

The reactions of transition metal trimethylacetates [Cu2(Piv)4(HPiv)2], [Ni9(OH)6(Piv)12(HPiv)4], [Co(Piv)2]n (Piv− = −O2CBut) with 1,1-cyclohexanediacetic acid (H2Chda) neutralized by tetrabutylammonium hydroxide in the presence of 2,2-bipyridine (2,2′-bpy) afford linear trinuclear homometallic complexes [(2,2′-bpy)2Cu3(Chda)2(Piv)2]··2EtOH (1) and [(2,2′-bpy)2M3(Chda)2(Piv)2(EtOH)2] (M = NiII (2) or CoII (3)). In molecules of these compounds, anions of both mono- and dicarboxylic acids act as bridges between the transition metal atoms. Compounds 1–3 were characterized by X-ray diffraction, and their magnetic properties were studied. Spin-spin ferromagnetic interactions dominate in complexes 1–3 with CuII (S = 1/2) (1) and CoII (S = 3/2) (3) ions.

Effect of the Structure of Pyridine Ligands and the Substituent in the Carboxylate Anion on the Geometry of Transition Metal Complexes [M 2 (O 2 CR) 4 L 2 ]

A series of binuclear tetracarboxylate-linked Mn(II), Fe(II), Co(II), Ni(II), and Cu(II) complexes with 1,2-substituted pyridine, viz., 2,3-cyclododecenopyridine (L), were prepared. Study of the crystal structures of isolated compounds (CIF file CCDC nos. 1575855–1575859) revealed a distortion of the {Ni2(O2CR)4L2} binuclear moiety, manifested as a change in the NiNiN angle (151.67°), in the bridging function of two out of the four carboxylate groups (from μ2- to (κ2,μ2-)), and in the coordination environment of the metal ion (NiO5N). The results were analyzed in comparison with known data. The magnetic properties of copper(II) and nickel(II) complexes were studied. The copper(II) complex is diamagnetic as a result of strong exchange interactions between the unpaired electrons; in the nickel(II) complex antiferromagnetic exchange interactions were detected (JNi–Ni =–25 cm–1).

Heterometallic trinuclear {CdII—MII—CdII} pivalates (M = Mg, Ca, or Sr): ways of assembly and structural features

Conditions for chemical assembly of new heterometallic trinuclear pivalates [Cd2M(piv)6L2] (M = Mg, Ca, or Sr; piv is pivalate) were found. Reactions with the nonchelating ligand 2,4-lutidine (lut) gave the crystals of heterometallic complexes [Cd2M(piv)6(lut)2] (M = Mg (1), Ca (2), and Sr (3)). With the chelating ligand 1,10-phenanthroline (phen), only the homometallic dimer [Cd2(piv)4(phen)2] (4) was obtained under these conditions. Yet heterometallic trinuclear complexes with 1,10-phenanthroline ([Cd2Mg(piv)6(H2O)(phen)2] (5), [CaCd2(piv)6(phen)2] (6), and [Cd2Sr(piv)6(phen)2]∙2MeCN (7)) were synthesized by reactions of phen with complexes 1—3. For all the complexes obtained, the molecular and crystal structures as well as the details of their molecular architecture were determined. The thermal behavior of aqua complex 5 was studied by TG and DSC. The complex eliminated the water molecule between 130 and 180 °C with a high endothermic effect (Q = 101 kJ mol–1) due to (1) intramolecular hydrogen bonds that stabilize its molecular architecture and (2) subsequent structural rearrangements.

Effect of geometric parameters of substituted malonate anions on coordination environment of CuII atoms coordinated with 2,2′;6′,2″-terpyridine

Structural data for known and newly obtained copper(II) complexes with 2,2′;6′,2″-terpyridine and substituted malonic (dimethylmalonic, 1,1-cyclopropane- and 1,1-cyclobutanedicarboxylic) acid dianions R2mal2- were used to show that the coordination environment of the metallocenter depends on the (O2C)C—C—C(CO2) angle. A chelate coordination of the R2mal2- dianion is realized for 1,1-cyclopropanedicarboxylate anion (~122.9°), while the dimethylmalonate and 1,1-cyclobutanedicarboxylate anions (107.4–110.8°) are characterized by a monodentate coordination.