Qualitative sign stability of linear time invariant descriptor systems

This article discusses assessing the instability of a continuous linear homogeneous timeinvariant descriptor system. Some necessary conditions and sufficient conditions are derived to establish the stability of a matrix pair by the fundamentals of qualitative ecological principles. The proposed conditions are derived using only the qualitative (sign) information of the matrix pair elements. Based on these conditions, the instability of a matrix pair can easily be determined, without any magnitude information of the matrix pair elements and without numerical eigenvalues calculations. With the proposed theory, Magnitude Dependent Stable, Magnitude Dependent Unstable, and Qualitative Sign Stable matrix pairs can be distinguished. The consequences of the proposed conditions and some illustrative examples are discussed

Triazole appended BODIPY–piperazine conjugates and their efficacy toward mercury sensing

An expeditious synthesis of new click reaction-based BODIPY–piperazine conjugates separated by alkyl spacers (4–7) has been described. The compounds under investigation have been thoroughly characterized by various physicochemical techniques viz., elemental analyses, IR, HRMS, NMR (<SUP>1</SUP>H, <SUP>13</SUP>C, <SUP>11</SUP>B and <SUP>19</SUP>F), electronic absorption, emission and theoretical studies. The comparative sensing abilities of 4–7 toward a range of metal ions have been investigated by various methods. Among these compounds, only 7 exhibited appreciable selectivity towards Hg<SUP>2+</SUP>, while the others remained inactive in the presence of various metal ions. Binding constant and Job's plot analysis indicated 1 : 1 stoichiometry between 7 and Hg<SUP>2+</SUP>. HRMS data and theoretical studies undoubtedly indicated the formation of a 7&#183;Hg<SUP>2+</SUP> complex and interaction of Hg<SUP>2+</SUP> with the probe via nitrogen atoms in the piperazine and triazole units

Synthesis, characterization, DNA binding and cytotoxicity of fluoro-dipyrrin based arene ruthenium(II) complexes

Synthesis of four new arene ruthenium(II) complexes [(eta(6)-C10H14)RuCl(MFPdpm)] (1); [(eta(6)-C12H18)Ru-Cl (MFPdpm)] (2); [(eta(6)-C10H14)RuCl(PFPdpm)] (3) and [(eta(6)-C12H18)RuCl(PFPdpm)] (4) containing dipyrrin ligands 5-(4-fluoro)phenyldipyrromethene (MFPdpm) and 5-(penta-fluoro)phenyldipyrromethene (PFPdpm) have been described. The ligands and complexes have been thoroughly characterized by elemental analyses, spectroscopic studies (ESI-MS, IR, H-1, C-13 NMR, UV-Vis) and structure of the representative complex 4 determined by X-ray single crystal analyses. DNA binding activities of 1-4 have been investigated by UV-Vis and fluorescence spectroscopy and their binding through the minor groove of DNA has been established by molecular docking studies. The complexes 1-4 exhibit significant cytotoxicity toward human lung cancer cell line (A549). Cytotoxicity, morphological changes, and apoptosis studies have been evaluated through MIT assay, Hoechst 333421131 staining, and cell cycle analysis by fluorescence activated cell sorting (FACS). In vitro antitumor activity and cytotoxicity of the complexes lie in the order 4 > 3 > 2 > 1. (C) 2016 Elsevier B.V. All rights reserved

Interaction of ferrocene appended Ru(II), Rh(III) and Ir(III) dipyrrinato complexes with DNA/protein, molecular docking and antitumor activity

Efficacy of the ferrocene appended piano-stool dipyrrinato complexes [(η6-C6H6)RuCl(fcdpm)](1), [(η6C10H14)RuCl(fcdpm)](2), [(η6-C12H18)RuCl(fcdpm)](3) [(η5-C5Me5)RhCl(fcdpm)](4) and [(η5-C5Me5IrCl(fcdpm)] (5) [fcdpm = 5-ferrocenyldipyrromethene] toward anticancer activity have been described. Binding of the complexes with calf thymus DNA (CT-DNA) and BSA (bovine serum albumin) have been thoroughly investigated by UV–Vis and fluorescence spectroscopy. Binding constants for 1–5 (range, 104–105 M-1) validated their efficient binding with CT-DNA. Molecular docking studies revealed interaction through minor groove of the DNA, on the other hand these also interact through hydrophobic residues of the protein, particularly cavity in the subdomain IIA. In vitro anticancer activity have been scrutinized by MTT assay, acridine orange/ethidium bromide (AO/EtBr) fluorescence staining, and DNA ladder (fragmentation) assay against Dalton's Lymphoma (DL) cells. Present study revealed that rhodium complex (4) is more effective relative to ruthenium (1–3) and iridium (5) complexes

Anticancer Activity of Iridium(III) Complexes Based on a Pyrazole-Appended Quinoline-Based BODIPY

A pyrazole-appended quinoline-based 4,4-difluoro-4-bora-3a,4a-diaza-<i>s</i>-indacene (<b>L1</b>, BODIPY) has been synthesized and used as a ligand for the preparation of iridium­(III) complexes [Ir­(phpy)₂(<b>L1</b>)]­PF₆ (<b>1</b>; phpy = 2-phenylpyridine) and [(η⁵-C₅Me₅)­Ir­(<b>L1</b>)­Cl]­PF₆ (<b>2</b>). The ligand <b>L1</b> and complexes <b>1</b> and <b>2</b> have been meticulously characterized by elemental analyses and spectral studies (IR, electrospray ionization mass spectrometry, ¹H and ¹³C NMR, UV/vis, fluorescence) and their structures explicitly authenticated by single-crystal X-ray analyses. UV/vis, fluorescence, and circular dichroism studies showed that complexes strongly bind with calf-thymus DNA and bovine serum albumin. Molecular docking studies clearly illustrated binding through DNA minor grooves via van der Waals forces and their electrostatic interaction and occurrence in the hydrophobic cavity of protein (subdomain IIA). Cytotoxicity, morphological changes, and apoptosis have been explored by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Hoechst 33342 staining. IC₅₀ values for complexes (<b>1</b>, 30 μM; <b>2</b>, 50 μM) at 24 h toward the human cervical cancer cell line (HeLa) are as good as that of cisplatin (21.6 μM) under analogous conditions, and their ability to kill cancer cells lies in the order <b>1</b> > <b>2</b>. Because of the inherent emissive nature of the BODIPY moiety, these are apt for intracellular visualization at low concentration and may find potential applications in cellular imaging and behave as a theranostic agent

Solvent-Dependent Self-Assembly and Aggregation-Induced Emission in Zn(II) Complexes Containing Phenothiazine-Based Terpyridine Ligand and Its Efficacy in Pyrophosphate Sensing

Zn­(II) complexes <b>MTPY–ZnCl</b>_<b>2</b> (<b>C1</b>) and <b>MTPY–Zn­(NO</b>_<b>3</b><b>)</b>_<b>2</b> (<b>C2</b>) based on a new D–A type ligand <b>MTPY</b> involving phenothiazine donor and terpyridine acceptor units have been described. The ligand <b>MTPY</b> and complexes <b>C1</b> and <b>C2</b> display intramolecular charge transfer and substantial solvatochromism. Solid-state emission studies on <b>MTPY</b> further substantiated the occurrence of concentration-induced emission in this molecule. In addition, the complexes <b>C1</b> and <b>C2</b> displayed a solvent-dependent self-assembly which has been examined as a function of the hydrophilic and hydrophobic nature of the solvent systems. The role of hydrophilicity/hydrophobicity of a solvent and compounds on morphology and emission characteristics of the self-assembled aggregates has been investigated by UV–vis, emission, and scanning electron microscopy studies. In addition, it has been categorically shown that aggregation-induced emission in <b>C1</b> offers a simple, sensitive, and rapid means for the detection of pyrophosphates (<b>PPi</b>) in the aqueous medium. Job’s plot analysis suggested a 3:1 binding stoichiometry between <b>C1</b> and <b>PPi</b>, which has been supported by electrospray ionization mass spectrometry and density functional theory. Further, higher affinity of <b>PPi</b> toward <b>C1</b> over <b>C2</b> has also been rationalized by theoretical studies

Synthesis, Structure, DNA/Protein Binding, and Anticancer Activity of Some Half-Sandwich Cyclometalated Rh(III) and Ir(III) Complexes

The Schiff base ligands benzylidene­(4-<i>tert</i>-butylphenyl)­amine 4-methyl ester (<b>L1</b>), (4-nitrobenzylidene)­(4-<i>tert</i>-butylphenyl)­amine (<b>L2</b>), and (4-cyanobenzylidene)­(4-<i>tert</i>-butylphenyl)­amine (<b>L3</b>) and the new series of cyclometalated mononuclear piano-stool complexes [(η⁵-C₅Me₅)­RhCl­(<b>L1</b>)] (<b>1</b>), [(η⁵-C₅Me₅)­RhCl­(<b>L2</b>)] (<b>2</b>), [(η⁵-C₅Me₅)­RhCl­(<b>L3</b>)] (<b>3</b>), [(η⁵-C₅Me₅)­IrCl­(<b>L1</b>)] (<b>4</b>), [(η⁵-C₅Me₅)­IrCl­(<b>L2</b>)] (<b>5</b>), and [(η⁵-C₅Me₅)­IrCl­(<b>L3</b>)] (<b>6</b>) have been synthesized. The ligands <b>L1</b>–<b>L3</b> and complexes <b>1</b>–<b>6</b> have been thoroughly characterized by satisfactory elemental analyses, spectral studies (ESI-MS, IR, ¹H and ¹³C NMR, UV–vis), and structures of <b>1</b>–<b>3</b> authenticated by X-ray single-crystal analyses. Efficient binding of <b>1</b>–<b>6</b> with calf thymus DNA (CT DNA) have been established by UV–vis and emission spectroscopic studies. Protein binding (bovine serum albumin, BSA) has been investigated by UV–vis, fluorescence, synchronous, and 3D fluorescence spectroscopy. Binding of the complexes with DNA through minor groove and hydrophobic interaction with proteins via sub domain IIA cavity has been substantiated by molecular docking studies. The complexes exhibited significant cytotoxicity against the human lung cancer cell line (A549), and <b>1</b> and <b>2</b> showed better activity than cisplatin. The cytotoxicity, morphological changes, and apoptosis have been assessed by MTT assay, Hoechst 33342/PI staining, cell cycle analysis by fluorescence-activated cell sorting (FACS), and reactive oxygen species (ROS) generation by DCFH-DA dye. The complexes <b>1</b>–<b>6</b> induce apoptosis in the order <b>2</b> > <b>1</b> > <b>4</b> > <b>3</b> > <b>5</b> > <b>6</b>

Synthesis, Structure, DNA/Protein Binding, and Anticancer Activity of Some Half-Sandwich Cyclometalated Rh(III) and Ir(III) Complexes

The Schiff base ligands benzylidene­(4-<i>tert</i>-butylphenyl)­amine 4-methyl ester (<b>L1</b>), (4-nitrobenzylidene)­(4-<i>tert</i>-butylphenyl)­amine (<b>L2</b>), and (4-cyanobenzylidene)­(4-<i>tert</i>-butylphenyl)­amine (<b>L3</b>) and the new series of cyclometalated mononuclear piano-stool complexes [(η⁵-C₅Me₅)­RhCl­(<b>L1</b>)] (<b>1</b>), [(η⁵-C₅Me₅)­RhCl­(<b>L2</b>)] (<b>2</b>), [(η⁵-C₅Me₅)­RhCl­(<b>L3</b>)] (<b>3</b>), [(η⁵-C₅Me₅)­IrCl­(<b>L1</b>)] (<b>4</b>), [(η⁵-C₅Me₅)­IrCl­(<b>L2</b>)] (<b>5</b>), and [(η⁵-C₅Me₅)­IrCl­(<b>L3</b>)] (<b>6</b>) have been synthesized. The ligands <b>L1</b>–<b>L3</b> and complexes <b>1</b>–<b>6</b> have been thoroughly characterized by satisfactory elemental analyses, spectral studies (ESI-MS, IR, ¹H and ¹³C NMR, UV–vis), and structures of <b>1</b>–<b>3</b> authenticated by X-ray single-crystal analyses. Efficient binding of <b>1</b>–<b>6</b> with calf thymus DNA (CT DNA) have been established by UV–vis and emission spectroscopic studies. Protein binding (bovine serum albumin, BSA) has been investigated by UV–vis, fluorescence, synchronous, and 3D fluorescence spectroscopy. Binding of the complexes with DNA through minor groove and hydrophobic interaction with proteins via sub domain IIA cavity has been substantiated by molecular docking studies. The complexes exhibited significant cytotoxicity against the human lung cancer cell line (A549), and <b>1</b> and <b>2</b> showed better activity than cisplatin. The cytotoxicity, morphological changes, and apoptosis have been assessed by MTT assay, Hoechst 33342/PI staining, cell cycle analysis by fluorescence-activated cell sorting (FACS), and reactive oxygen species (ROS) generation by DCFH-DA dye. The complexes <b>1</b>–<b>6</b> induce apoptosis in the order <b>2</b> > <b>1</b> > <b>4</b> > <b>3</b> > <b>5</b> > <b>6</b>