Ligand-Isomerism Controlled Structural Diversity of Zn(II) and Cd(II) Coordination Polymers from Mixed Dipyridyladipoamide and Benzenedicarboxylate Ligands

By using isomeric <i>N</i>,<i>N′</i>-di­(2-pyridyl)­adipoamide (<b>L</b>^<b>1</b>), <i>N</i>,<i>N′</i>-di­(3-pyridyl)­adipoamide (<b>L</b>^<b>2</b>) and <i>N</i>,<i>N′</i>-di­(4-pyridyl)­adipoamide (<b>L</b>^<b>3</b>) and isomeric 1,2-benzenedicarboxylic acid (1,2-H₂BDC), 1,3-benzenedicarboxylic acid (1,3-H₂BDC) and 1,4-benzenedicarboxylic acid (1,4-H₂BDC), eight Zn­(II) and Cd­(II) coordination polymers [Zn­(1,2-BDC)­(<b>L</b>^<b>2</b>)]_∞, <b>1</b>; [Zn₂(1,3-BDC)₂(<b>L</b>^<b>2</b>)­(H₂O)₂]_∞, <b>2</b>; [Zn₂(1,4-BDC)₂(<b>L</b>^<b>1</b>)­(H₂O)₂]_∞, <b>3</b>; {[Zn₂(1,2-BDC)₂(<b>L</b>^<b>3</b>)­(H₂O)₂]·2H₂O}_∞, <b>4</b>; {[Cd­(1,2-BDC)­(<b>L</b>^<b>2</b>)­(H₂O)]­·H₂O}_∞, <b>5</b>; [Cd₂(1,3-BDC)₂(<b>L</b>^<b>2</b>)­(H₂O)₄]_∞, <b>6</b>; {[Cd₂(1,4-BDC)₂(<b>L</b>^<b>2</b>)₂]­·(H₂O)₃}_∞, <b>7</b>; [Cd₂(1,4-BDC)₂(<b>L</b>^<b>1</b>)­(H₂O)₂]_∞, <b>8</b>, have been synthesized under hydrothermal conditions. Complexes <b>1</b>, <b>4</b>, and <b>5</b> form 1D double-looped chain, 1D chain with loops and 2D layer with loops, respectively, and complex <b>6</b> exhibits a 1D ladder chain. Complex <b>2</b> shows rare 3-fold interpenetrated <b>hcb</b> layers, in which each layer interdigitates with other four parallel layers by directing the 1,3-BDC ligands into the windows of the adjacent nets, whereas complexes <b>3</b> and <b>8</b> forms planar and undulated <b>hcb</b> layers, respectively. Complex <b>7</b> shows a 3D self-penetrating net of {4²⁴.5.6³}-<b>ilc</b> topology with a unique arrangement for the <b>L</b>^<b>2</b> spacer ligands. The <b>L</b>^<b>1</b> ligands in complexes <b>3</b> and <b>8</b> adopt the new tetradentate bonding mode involving chelation and bridge through two pyridyl nitrogen atoms and two amide oxygen atoms, whereas the <b>L</b>^<b>2</b> and <b>L</b>^<b>3</b> ligands in other complexes show the bidentate bonding mode through the two pyridyl nitrogen atoms. The various bonding modes and the ligand-isomerism of the spacer ligands BDC^2– and <b>L</b>^<b>1</b>–<b>L</b>^<b>3</b> as well as the identity of the metal center play important roles in determining the structural diversity

Ag(I) Complexes Containing Flexible <i>N</i>,<i>N′</i>-Di(3-pyridyl)adipoamide Ligands: Syntheses, Structures, Ligand Conformations, and Crystal-to-Crystal Transformations

The reactions of <i>N</i>,<i>N′</i>-di­(3-pyridyl)­adipoamide (<b>L</b>) with the corresponding silver­(I) salts afforded the complexes {[Ag­(<b>L</b>)]­(PF₆)·2CH₃CN}_∞, <b>1</b>, {[Ag­(<b>L</b>)]­(BF₄)·CH₃CN}_∞, <b>2</b>, {[Ag­(<b>L</b>)]­(NO₃)·CH₃CN}_∞, <b>3</b>, {[Ag­(<b>L</b>)]­(PF₆)·4DMF}_∞, <b>4</b>, {[Ag­(<b>L</b>)]­(BF₄)·4DMF}_∞, <b>5</b>, {[Ag­(<b>L</b>)]­(CF₃SO₃)·DMF}_∞, <b>6</b>, {[Ag­(<b>L</b>)]­(ClO₄)·CH₃CN}_∞, <b>7</b>, {[Ag­(<b>L</b>)]­(ClO₄)}_∞, <b>8</b>, [Ag₂(<b>L</b>)₂]­(<i>p</i>-TsO)₂·2CH₃CN (<i>p</i>-TsO = <i>p</i>-toluenesulfonate), <b>9</b>, and [Ag­(<b>L</b>)­(<i>p</i>-TsO)]_∞, <b>10</b>. Complex <b>1</b> forms a one-dimensional (1D) concavo-convex chain, and complexes <b>2</b>, <b>3</b>, <b>6</b>, and <b>7</b> show 1D polymeric pairs of zigzag chains supported by the Ag---Ag and π–π interactions, whereas complexes <b>4</b>, <b>5</b>, and <b>8</b> adopt zigzag chains. Complex <b>9</b> forms a zero-dimensional (0D) dinuclear metallocycle, and complex <b>10</b> shows a two-dimensional (2D) pleated grid with a {4,8²} topology, respectively. The <b>L</b> ligands in these complexes adopt various ligand conformations, which are subjected to the changes of the counteranions and solvents, resulting in the different structural types. Reversible crystal-to-crystal transformation was observed in <b>7</b> and <b>8</b> upon removal and uptake of the acetonitrile molecules, while the process was irreversible in <b>9</b> and <b>10</b>, which is concomitant with changes in supramolecular structures, ligand conformations, and luminescent properties. The main driving forces for the structural transformations are the Ag---N and Ag---O interactions

Infection of <i>C. elegans</i> by <i>B. anthracis-gfp</i> in presence of <i>B. thuringiensis</i> expressing Cry5B spores (non-<i>gfp</i>) and <i>B. anthracis-gfp</i> spores.

<p>(A) Transmitted-light view of the worm cuticle filled with vegetative and sporulated Bacillus. (B) View of the same worm using the fluorescence light: rod-shaped bacteria expressing GFP are visible, indicating that <i>B. anthracis</i> is capable of infecting <i>C. elegans</i> in presence of Cry5B expressing-<i>B. thuringiensis</i>. In this animal and all similar animals examined, the vast majority of bacteria inside the nematode cuticle were GFP positive. Scale bar is 50 µm.</p

Infectivity of <i>Bacillus</i> sp. on <i>C. elegans</i> in the presence/absence of pore-forming Cry5B.

<p>Infectivity of <i>Bacillus</i> sp. on <i>C. elegans</i> in the presence/absence of pore-forming Cry5B.</p

Infection of <i>C. elegans</i> by <i>B. thuringiensis</i> and <i>B. anthracis</i>.

<p>Top row: Dissecting microscope view of nematodes cultured under various conditions. Scale bar of all images in top row is 500 µm. Bottom row: Compound microscope view of nematodes cultured under various conditions. For all images in the bottom row, anterior of the worm is top right and scale bar is 50 µm. (A) <i>C. elegans</i> cultured in a well with <i>B. thuringiensis</i> without Cry5B. Top row: None of the six nematodes are infected. All are healthy. The blur associated with some of the worms in the top row is due to their movement in the well. Bottom row: The internal structures of <i>C. elegans</i> fed <i>B. thuringiensis</i> without Cry5B, including the pharynx and intestine, are all intact. (B) <i>C. elegans</i> cultured in a well with <i>B. thuringiensis</i> and Cry5B. Top row: Five of the six worms are completely infected (rigid, lack of internal structures and normal coloration); one is not. Bottom row: Infected animals show complete or near complete digestion of internal structures by the bacteria. Vegetative and sporulated bacteria can be seen in these lethally infected animals. (C) Similar images as in (B) except the bacterium cultured with the nematodes is <i>Bacillus anthracis</i>.</p

Infection of <i>C. elegans</i> by different <i>Bacillus</i> species.

<p>The percent-infected worms by different Bacillus are shown along with standard error. Means below the same letter were not significantly different at <i>P<0.05</i>; means below different letters are significantly different at <i>P<0.05</i>. Each bar represents the mean for 3–4 independent trials. The total number of animals screened from left to right are: 117, 209, 117, 122, 107, 142, 96, 96, 96, 72, 96, and 216.</p

Infectivity of <i>B. anthracis</i> in the presence of Cry-plus B. <i>thuringiensis.</i>

<p>Infectivity of <i>B. anthracis</i> in the presence of Cry-plus B. <i>thuringiensis.</i></p

Temporal aspects of the infection process.

<p>(A) Infections are established upon a short exposure to pathogen. Upper: schematic of experiment. Worms are added to the well on the left containing <i>B. thuringiensis</i> and Cry5B. Following either 5 min, 15 min, 30 min, 1 h, 2 h, 4 h, or 8 h, the worms were then moved through a series of five wells lacking Cry5B protein and containing non-infectious <i>B. megaterium</i> instead of <i>B. thuringiensis</i>. Infection outcomes in the final well were scored 48 h later. Lower: results of the experiment depicted in upper schematic. Data shown represent a total of three independent experiments with ∼30 animals per time point per experiment. Error bars indicate SEM. Only the infection rate for a 5-minute pulse is significantly different from the other data points (ANOVA, <i>p</i><0.05, Tukey's post test). (B) Cry5B acts early in the infection process as temporal addition of Cry5B protein after, and separate from, pathogen exposure results in a significant drop in infections. Upper: schematic of experiment in which worms are exposed to pathogen first and then to Cry5B. Lower: results in which two sets of experiments were set up simultaneously—a normal 15 minute pulse chase with both Cry5B PFP and pathogen added together (light gray bars; see (A) for set up) and pulse chase in which Cry5B was not added until the end (dark gray bars). Error bars represent SEM. ∼30 worms/condition/trial; 3–4 independent trials per condition. (C) The infection process appears to begin with colonization of the anterior intestine. The anterior intestine of a nematode 3 hr after exposure to <i>B. thuringiensis</i> (407-gfp) under pathogenic conditions. The left panel is a DIC image; the right panel deconvolved fluorescent (FITC) of the same animal. Images taken at 600×. Anterior is down.</p