Self-Assembly of Discrete Metallocycle versus Coordination Polymer Based on Silver(I) and Di-2- and Di-3-pyridines with Flexible Spacer

Four flexible bis(pyridyl) ligands, namely, 1,3-bis(2-pyridylaminomethyl)benzene (L1), 1,3-bis(3-pyridylaminomethyl)benzene (L2), 1,4-bis(3-pyridylaminomethyl)benzene (L3), and 1,4-bis(2-pyridylaminomethyl)benzene (L4), have been synthesized, and the reactions of these ligands with AgX salts (X = NO3−, ClO4−) lead to the formation of six new complexes, [Ag(L1)]2(ClO4)2 (1), [Ag(L2)ClO4]n (2), [Ag(L1)NO3]n (3), [Ag(L3)(PPh3)2]n(NO3)n·nCH3OH (4), [Ag2(L4)(PPh3)2(NO3)2]n·nH2O (5), and [Ag(L4)NO3]n (6), exhibiting from zero-dimensional (0-D) to three-dimensional (3-D) frameworks. In complex 1, the L1 ligand bridges two silver atoms to form a dinuclear with a 24-membered macrometallacyclic ring, while the L1 ligand coordinates to silver atoms to generate a 2-D (4,4) network with two pyridine rings oriented in a divergent fashion (or trans conformation) in complex 3. With a similar trans conformation, L2 in complex 2, L3 in complex 4, and L4 in complex 5 connect the adjacent silver atoms or Ag2O2 units which formed by the bridging of nitrate anions in a η2:μ2 fashion to give rise to infinite helical chains, respectively. Complex 6 exhibits a 3-D framework with diamond topology, which is combined by two kinds of helical chains: one is a -Ag-NO3-Ag-NO3- chain with the nitrate anions in a η1:η1:μ2 fashion, and another is a -Ag-L4-Ag-L4- chain with the L4 ligand in trans conformation. All of these complexes are photoluminescent in the solid state with spectra that closely resemble those of the ligand precursor

Self-Assembly of Discrete Metallocycle versus Coordination Polymer Based on Silver(I) and Di-2- and Di-3-pyridines with Flexible Spacer

Four flexible bis(pyridyl) ligands, namely, 1,3-bis(2-pyridylaminomethyl)benzene (L1), 1,3-bis(3-pyridylaminomethyl)benzene (L2), 1,4-bis(3-pyridylaminomethyl)benzene (L3), and 1,4-bis(2-pyridylaminomethyl)benzene (L4), have been synthesized, and the reactions of these ligands with AgX salts (X = NO3−, ClO4−) lead to the formation of six new complexes, [Ag(L1)]2(ClO4)2 (1), [Ag(L2)ClO4]n (2), [Ag(L1)NO3]n (3), [Ag(L3)(PPh3)2]n(NO3)n·nCH3OH (4), [Ag2(L4)(PPh3)2(NO3)2]n·nH2O (5), and [Ag(L4)NO3]n (6), exhibiting from zero-dimensional (0-D) to three-dimensional (3-D) frameworks. In complex 1, the L1 ligand bridges two silver atoms to form a dinuclear with a 24-membered macrometallacyclic ring, while the L1 ligand coordinates to silver atoms to generate a 2-D (4,4) network with two pyridine rings oriented in a divergent fashion (or trans conformation) in complex 3. With a similar trans conformation, L2 in complex 2, L3 in complex 4, and L4 in complex 5 connect the adjacent silver atoms or Ag2O2 units which formed by the bridging of nitrate anions in a η2:μ2 fashion to give rise to infinite helical chains, respectively. Complex 6 exhibits a 3-D framework with diamond topology, which is combined by two kinds of helical chains: one is a -Ag-NO3-Ag-NO3- chain with the nitrate anions in a η1:η1:μ2 fashion, and another is a -Ag-L4-Ag-L4- chain with the L4 ligand in trans conformation. All of these complexes are photoluminescent in the solid state with spectra that closely resemble those of the ligand precursor

Fluorescence spectra of TMPipEOPP in the absence or presence of different DNAs when excited at 422 nm.

<p>[TMPipEOPP] = 5 µM. [DNA] = 10 µM (strand concentration). [CtDNA] = 240 µM (base concentration).</p

Asymmetric Cationic Porphyrin as a New G‑Quadruplex Probe with Wash-Free Cancer-Targeted Imaging Ability Under Acidic Microenvironments

Porphyrins are promising candidates for nucleic acid G-quadruplex-specific optical recognition. We previously demonstrated that G-quadruplex recognition specificity of porphyrins could be improved by introducing bulky side arm substituents, but the enhanced protonation tendency limits their applications in some cases, such as under acidic conditions. Here, we demonstrated that the protonation tendency of porphyrin derivatives could be efficiently overcome by increasing molecular asymmetry. To validate this, an asymmetric, water-soluble, cationic porphyrin FA-TMPipEOPP (5-{4-[2-[[(2<i>E</i>)-3-[3-methoxy-4-[2-(1-methyl-1-piperidinyl)­ethoxy]­phenyl]-1-oxo-2-propenyl]­oxy]­ethoxy]­phenyl},10,15,20-tri­{4-[2-(1-methyl-1-piperidinyl)­ethoxy]-phenyl}­porphyrin) was synthesized by introducing a ferulic acid (FA) unit at one side arm, and its structure was well-characterized. Unlike its symmetric counterpart TMPipEOPP that has a tendency to protonate under acidic conditions, FA-TMPipEOPP remained in the unprotonated monomeric form under the pH range of 2.0–8.0. Correspondingly, FA-TMPipEOPP showed better G-quadruplex recognition specificity than TMPipEOPP and thus might be used as a specific optical probe for colorimetric and fluorescent recognition of G-quadruplexes under acidic conditions. The feasibility was demonstrated by two proof-of-concept studies: probing structural competition between G-quadruplexes and duplexes and label-free and wash-free cancer cell-targeted bioimaging under an acidic tumor microenvironment. As G-quadruplex optical probes, FA-TMPipEOPP works well under acidic conditions, whereas TMPipEOPP works well under neutral conditions. This finding provides useful information for G-quadruplex probe research. That is, porphyrin-based G-quadruplex probes suitable for different pH conditions might be obtained by adjusting the molecular symmetry

Self-Assembly of Discrete Metallocycle versus Coordination Polymer Based on Silver(I) and Di-2- and Di-3-pyridines with Flexible Spacer

Four flexible bis(pyridyl) ligands, namely, 1,3-bis(2-pyridylaminomethyl)benzene (L1), 1,3-bis(3-pyridylaminomethyl)benzene (L2), 1,4-bis(3-pyridylaminomethyl)benzene (L3), and 1,4-bis(2-pyridylaminomethyl)benzene (L4), have been synthesized, and the reactions of these ligands with AgX salts (X = NO3−, ClO4−) lead to the formation of six new complexes, [Ag(L1)]2(ClO4)2 (1), [Ag(L2)ClO4]n (2), [Ag(L1)NO3]n (3), [Ag(L3)(PPh3)2]n(NO3)n·nCH3OH (4), [Ag2(L4)(PPh3)2(NO3)2]n·nH2O (5), and [Ag(L4)NO3]n (6), exhibiting from zero-dimensional (0-D) to three-dimensional (3-D) frameworks. In complex 1, the L1 ligand bridges two silver atoms to form a dinuclear with a 24-membered macrometallacyclic ring, while the L1 ligand coordinates to silver atoms to generate a 2-D (4,4) network with two pyridine rings oriented in a divergent fashion (or trans conformation) in complex 3. With a similar trans conformation, L2 in complex 2, L3 in complex 4, and L4 in complex 5 connect the adjacent silver atoms or Ag2O2 units which formed by the bridging of nitrate anions in a η2:μ2 fashion to give rise to infinite helical chains, respectively. Complex 6 exhibits a 3-D framework with diamond topology, which is combined by two kinds of helical chains: one is a -Ag-NO3-Ag-NO3- chain with the nitrate anions in a η1:η1:μ2 fashion, and another is a -Ag-L4-Ag-L4- chain with the L4 ligand in trans conformation. All of these complexes are photoluminescent in the solid state with spectra that closely resemble those of the ligand precursor

Self-Assembly of Discrete Metallocycle versus Coordination Polymer Based on Silver(I) and Di-2- and Di-3-pyridines with Flexible Spacer

Four flexible bis(pyridyl) ligands, namely, 1,3-bis(2-pyridylaminomethyl)benzene (L1), 1,3-bis(3-pyridylaminomethyl)benzene (L2), 1,4-bis(3-pyridylaminomethyl)benzene (L3), and 1,4-bis(2-pyridylaminomethyl)benzene (L4), have been synthesized, and the reactions of these ligands with AgX salts (X = NO3−, ClO4−) lead to the formation of six new complexes, [Ag(L1)]2(ClO4)2 (1), [Ag(L2)ClO4]n (2), [Ag(L1)NO3]n (3), [Ag(L3)(PPh3)2]n(NO3)n·nCH3OH (4), [Ag2(L4)(PPh3)2(NO3)2]n·nH2O (5), and [Ag(L4)NO3]n (6), exhibiting from zero-dimensional (0-D) to three-dimensional (3-D) frameworks. In complex 1, the L1 ligand bridges two silver atoms to form a dinuclear with a 24-membered macrometallacyclic ring, while the L1 ligand coordinates to silver atoms to generate a 2-D (4,4) network with two pyridine rings oriented in a divergent fashion (or trans conformation) in complex 3. With a similar trans conformation, L2 in complex 2, L3 in complex 4, and L4 in complex 5 connect the adjacent silver atoms or Ag2O2 units which formed by the bridging of nitrate anions in a η2:μ2 fashion to give rise to infinite helical chains, respectively. Complex 6 exhibits a 3-D framework with diamond topology, which is combined by two kinds of helical chains: one is a -Ag-NO3-Ag-NO3- chain with the nitrate anions in a η1:η1:μ2 fashion, and another is a -Ag-L4-Ag-L4- chain with the L4 ligand in trans conformation. All of these complexes are photoluminescent in the solid state with spectra that closely resemble those of the ligand precursor

Excitation spectra of TMPipEOPP in the absence or presence of different DNAs when the emission wavelength is held at 726 nm.

<p>[TMPipEOPP] = 5 µM. [DNA] = 10 µM (strand concentration). [CtDNA] = 240 µM (base concentration).</p

Fluorescence spectra of TMPipEOPP in the absence or presence of different DNAs when excited at 464 nm.

<p>[TMPipEOPP] = 5 µM. [DNA] = 10 µM (strand concentration). [CtDNA] = 240 µM (base concentration).</p

G-quadruplex discrimination from duplex and single-stranded DNA by the naked eyes.

<p>The DNA used in each tube is labeled at the top of the figure. [TMPipEOPP] = 5 µM. [DNA] = 10 µM (strand concentration). [CtDNA] = 240 µM (base concentration).</p

Molecular configuration for TPipEOPP•2.5MeOH.

<p>Hydrogen atoms and methanol solvent molecules are omitted for clarity.</p