Tetrakis Benzoic Acid Research Articles

Black phosphorus nanosheets adhering to thionine-doped 2D MOF as a smart aptasensor enabling accurate capture and ratiometric electrochemical detection of target microRNA

Novel two-dimensional (2D) metal-organic frameworks (MOF) were one-pot prepared by solvothermal reaction, using copper nitrate and 4,4’,4’’,4’’’-(porphine-5,10,15,20-tetrayl)tetrakis benzoic acid as precursors and thionine (TH) as the doping component. Black phosphorus nanosheets (BPNSs) were prepared by liquid-phase exfoliation of bulk crystals and were adhered to TH-doped 2D MOF (TH/Cu-MOF) to produce BPNSs/TH/Cu-MOF complex. The complex was drop-casted on glassy carbon electrode (GCE) to construct BPNSs/TH/Cu-MOF/GCE, followed by combining ferrocene (Fc)-labeled single-strand DNA aptamer to form aptamer-BPNSs/TH/Cu-MOF nanohybrid on GCE. The formation process of nanohybrid was characterized and experiment conditions were optimized. Under optimal conditions, the aptamer-BPNSs/TH/Cu-MOF/GCE platform served as a smart ratiometric electrochemical aptasensor that can accurately capture and detect microRNA (miR3123). With increase of miR3123 concentration (CmiR3123), the redox peak current of Fc (IFc) decreased, because special combination of Fc-aptamer with miR3123 led to Fc away from GCE surface. TH was doped into 2D MOF and its peak current (ITH) had negligible changes. TH and Fc acted as reference signal and response signal, respectively. There is a plotted linear relationship between (IFc/ITH) and logarithm of CmiR3123 in the range from 2 pM to 2 μM, together with a low limit of detection of 0.3 pM. The aptasensor had high sensitivity, selectivity and stability, and was applied to accurate detection of miR3123 in practical samples, showing high practicability.

Nonlinear optical behavior of porphyrin functionalized nanodiamonds: an efficient material for optical power limiting.

The nonlinear optical mechanisms and the optical limiting behavior of porphyrin functionalized detonation nanodiamonds are investigated and compared to the conventional detonation nanodiamonds (DNDs). The optical limiting behavior is characterized by means of nonlinear transmittance, Z-scan, and scattered intensity measurements when submitted to a nanosecond pulsed Nd:YAG laser operating at the second harmonic wavelength. We found that the largest nonlinear attenuation was observed on the 4,4',4'',4'''-(porphyrin-5, 10, 15, 20-tetrayl) tetrakis benzoic acid (PCOOH) suspension. Using Z-scan experiments, it is shown that nonlinear refraction predominates in the unfunctionalized DND suspension, while nonlinear absorption is the most relevant mechanism in the porphyrin functionalized DNDs. Furthermore, a stronger backscattered intensity signal is highlighted for the unfunctionalized DNDs through nonlinear scattering measurements.

MnTBAP Ameliorates Obesity and Metabolic Dysfunction and Limits the TF‐PAR2 Pro‐inflammatory Pathway in White Adipose Tissue

Obesity is a prevalent metabolic disease that is associated with increased reactive oxygen species and oxidative stress. The purpose of this study was to determine if the superoxide dismutase mimetic manganese tetrakis benzoic acid porphyrin (MnTBAP) can attenuate obesity and obesity-associated metabolic dysfunction. Mice were treated with MnTBAP or vehicle during the last five weeks of a 24 week high fat diet (HFD) regimen. Energy homeostasis, insulin sensitivity, adipose macrophage infiltrates, protein kinase B (PKB) and tissue factor - protease activated receptor 2 (TF-PAR2) pathways were assessed following MnTBAP treatment. MnTBAP treatment significantly reduced body weight and adipose tissue mass. The reduction in adiposity was associated with decreased caloric intake and improved insulin sensitivity. Protein kinase B (PKB) phosphorylation and expression were significantly increased in a tissue-specific manner in skeletal muscle and adipose tissue of HFD mice treated with MnTBAP. In addition, MnTBAP treatment decreased macrophage infiltrates in adipose tissue and reduced the pro-inflammatory TF-PAR2 pathway. Our data suggests that the ability of MnTBAP to improve insulin sensitivity is due to decreased adiposity, reduced adipose tissue inflammation, and increased PKB phosphorylation and expression. Further, our findings implicate decreased caloric intake and inhibition of the TF-PAR2 pathway in the anti-obesity and insulin-sensitizing effects of MnTBAP.

MnTBAP reduces diet‐induced adiposity independent of β‐adrenergic receptor signaling (854.8)

Manganese tetrakis benzoic acid porphyrin (MnTBAP) is a superoxide dismutase mimetic that has recently been shown to reduce visceral adiposity (Pires et al., 2013). In visceral fat of mice treated with MnTBAP, we have observed significant increases in hormone sensitive lipase activity and PGC‐1α expression. These observations indicate that MnTBAP may activate the sympathetic nervous system, which is known to stimulate lipolysis and brown/beige adipocyte activity. To test whether the ability of MnTBAP to reduce adiposity is dependent on β‐adrenergic receptor signaling, mice were fed a high fat diet (HFD) or a low fat diet (LFD) for six months. During the last six weeks of the dietary intervention mice were treated with MnTBAP alone or in combination with a β‐adrenergic receptor antagonist cocktail (β‐Blockers) containing propranolol and the β3‐adrenergic receptor antagonist SR59230A. Prior to treatment, mice fed a HFD weighed significantly more than mice fed a LFD, but no significant differences in body weight were observed among mice receiving vehicle, MnTBAP, or MnTBAP+β‐Blockers within a respective diet condition. Following the six week treatment period, mice fed a HFD that received MnTBAP or MnTBAP+β‐Blockers experienced a significant reduction in body weight and epididymal white adipose tissue (EWAT) mass than mice that received vehicle. These changes appeared to be related to caloric intake but not energy expenditure, as mice that received MnTBAP or MNTBAP+β‐Blockers consumed significantly less calories and had decreased energy expenditure compared to vehicle‐treated controls. Finally, there was no effect of MnTBAP treatment on UCP1 or Cidea expression in EWAT. Collectively, these results suggest that the ability of MnTBAP to reduce adiposity is independent of β‐adrenergic receptor signaling and indicate that MnTBAP decreases adiposity by regulating caloric intake.Grant Funding Source: Supported by NIH 1 R15 DK090722‐01

MnTBAP ameliorates diet‐induced insulin resistance by reducing adiposity and increasing AKT expression in skeletal muscle (854.7)

Manganese tetrakis benzoic acid porphyrin (MnTBAP) is a superoxide dismutase mimetic that decreases adiposity but does not improve insulin action in diet‐induced obese mice (Pires et al., 2013). In leptin deficient Ob/Ob mice, MnTBAP improves insulin sensitivity without reducing adiposity (Houstis et al., 2006). The present study investigated whether MnTBAP treatment improves leptin sensitivity and insulin action in diet‐induced obese mice. Mice were fed a high fat diet (HFD) or a low fat diet (LFD) for six months. During the last five weeks of the dietary intervention, HFD and LFD mice were treated with MnTBAP or vehicle. After one week of MnTBAP treatment, a time point at which caloric intake is reduced but no significant weight loss has occurred, leptin sensitivity was assessed by injecting mice with leptin and monitoring food intake. Although mice fed a HFD were leptin resistant, MnTBAP did not alter the ability of leptin to reduce food intake. After four weeks of MnTBAP treatment, a time point when significant weight loss has occurred in HFD mice, insulin sensitivity was assessed by an insulin‐assisted glucose tolerance test (IAGTT). Blood glucose values during the IAGT T were lower in HFD mice treated with MnTBAP compared to vehicle. MnTBAP treatment did not alter blood glucose values during the IAGT in LFD mice. Skeletal muscle from HFD mice treated with MnTBAP exhibited a significant increase in insulin‐stimulated phosphorylation of AKT. The increase in AKT phosphorylation in muscle was due to a significant increase in AKT1 and AKT2 protein expression, without significant changes in AKT1 and AKT2 mRNA levels, suggesting a post‐transcriptional mechanism. Taken together, our results indicate that MnTBAP improves insulin sensitivity by reducing adiposity and augmenting insulin signaling associated with increased AKT expression. The anti‐obesity action of MnTBAP is related to a reduction in caloric intake, a process that appears to be independent of changes in leptin sensitivity.Grant Funding Source: Supported by NIH 1 R15 DK090722‐01

Heme Oxygenase‐1 Inhibition Does Not Prevent MnTBAP's Ability to Reduce Adiposity and Increase Insulin Action

Metalloporphryins have been shown to cause weight loss by a heme oxygenase‐1 (HO‐1) dependent mechanism. The purpose of this study was to determine if inhibiting HO‐1 with tin mesoporphyrin (SnMP) prevents the reduction in adiposity and the improvement in insulin sensitivity due to manganese tetrakis benzoic acid porphyrin (MnTBAP) treatment. Mice were fed a low fat diet (LFD) or a high fat (HFD) for four months. During the last 30 days of the dietary intervention, mice were given intraperitoneal injections of MnTBAP (10 mg/kg/day), MnTBAP+SnMP (20 mg/kg/day), or vehicle. SnMP treatment did not prevent the ability of MnTBAP to significantly decrease body weight (Vehicle: 42.5±1.8 vs. MnTBAP: 36.7±1.4 vs. MnTBAP+SnMP: 35.8±1.0) or epididymal white adipose tissue (EWAT) weight (Vehicle: 2.52±0.10 vs. MnTBAP: 1.88±0.14 vs. MnTBAP+SnMP: 1.66±0.11). Insulin sensitivity was significantly higher in HFD mice treated with MnTBAP or MnTBAP+SnMP when compared to vehicle treated HFD mice. Since carbon monoxide (CO) is a product of the HO‐1 reaction, it may mediate the anti‐obesity effects of metalloporphyrins. However, treating HFD mice with CO (250 ppm, 1 hr/day, 4 weeks) did not result in a reduction in body weight or EWAT weight, and did not improve insulin sensitivity. These results indicate that the ability of MnTBAP to promote weight loss and improve insulin sensitivity is independent of HO‐1 activity.

MnTBAP Reduces Adiposity and Increases Bio‐markers for Mitochondrial Biogenesis

The purpose of this study was to determine if manganese tetrakis benzoic acid porphyrin (MnTBAP) treatment reduces adiposity and increases bio‐markers for mitochondrial biogenesis. Male C57B6 mice were fed a low fat diet (LFD) or a high fat (HFD) for five months. During the last 30 days of the dietary intervention, mice were given intraperitoneal injections of MnTBAP (10 mg/kg/day) or vehicle. MnTBAP treatment significantly decreased body weight (52.8±2 vs. 40.1±2.1) and epididymal white adipose tissue (EWAT) weight (2.53±0.11 vs. 1.47±0.13). PGC‐1α and nuclear respiratory factor‐1 (NRF1) were significantly higher in EWAT from mice treated with MnTBAP compared to mice treated with vehicle. Additionally, MnTBAP treatment increased the phosphorylation of AMPK on Thr 172, site whose phosphorylation is associated with increased AMPK activity. Because β‐adrenergic receptor activation can increase AMPK activity and PGC‐1α expression, we also examined the phosphorylation of hormone sensitive lipase (HSL) on Ser 563, the site phosphorylated by the cAMP dependent kinase (PKA). Phosphorylation of HSL was significantly increased in EWAT of mice treated with MnTBAP, indicating the activation of β‐adrenergic receptor signaling. Taken together, our data demonstrates that MnTBAP treatment reduces dietary‐induced obesity by a mechanism that may involve mitochondrial biogenesis.

Effects of Antioxidants on Endothelial Function in Human Saphenous Vein in an Ex vivo Model

This ex vivo study is aimed at determining the beneficial effects of antioxidant agents on human saphenous vein endothelial function. Vein rings harvested during infrainguinal bypass surgery were assessed in an organ bath for endothelium-dependent relaxation, initially without and then with the addition of 10 microM manganese tetrakis benzoic acid porphyrin (MnTBAP), 0.01% N-acetylcysteine (NAC), 0.02% NAC, 10 microM vitamin C, and 100 microM vitamin C. Fifty-five vein rings from 22 patients were analyzed. MnTBAP improved the endothelium-dependent relaxation when compared with control (57.0% vs 37.8%, P < .01). Addition of 0.01% or 0.02% NAC did not improve the endothelium-dependent vasorelaxation (28.2% vs 18.6%, P = ns and 37.8% vs 29.8%, P = ns, respectively). Although 10-microM vitamin C failed to improve endothelial function (50.6% vs 37.2%, P = ns), 100-microM vitamin C significantly enhanced endothelium-dependent relaxation (66.5% vs 38.3%, P < .001). These results suggest that the addition of MnTBAP and high-dose vitamin C can improve the endothelial function of harvested saphenous vein segments in an ex vivo model.

Oxidation catalysis of microporous metal carboxylate complexes

Abstract A microporous copper(II) carboxylate complex, copper(II) trans -1,4-cyclohexanedicarboxylate [Cu 2 II,II (OOCC 6 H 10 COO) 2 ]·H 2 O ( 1 ) can act as a biomimetic heterogeneous catalyst for selective oxidation of various alcohols with H 2 O 2 . A green-colored active intermediate, H 2 [Cu 2 II,II (OOCC 6 H 10 COO) 2 (O 2 )]·H 2 O ( 2 ), observed in the reaction of 1 with 20-fold excess H 2 O 2 in acetonitrile was characterized by elemental analysis, TG/DTA, magnetic susceptibility, FT-IR, diffuse reflectance (DR) UV–vis, electron paramagnetic resonance (EPR), X-ray powder diffraction (XRPD), resonance Raman, BET surface area, pore size distribution, and nitrogen occlusion measurements. The molecular structure of 2 was determined from XRPD data and refined by the Rietveld method. The microporous structure of 2 was constructed by intermolecular bridging of μ-1,2- trans Cu–OO–Cu species between two-dimensional [Cu 2 (O 2 CC 6 H 10 CO 2 )] layers, which was the first example of microporous copper(II) peroxo complex for heterogeneous oxidation catalysis. Moreover, a microporous ruthenium(II,III) complex having porphyrin [Ru II,III 2 (H 2 TCPP)]BF 4 ( 3 ) (H 2 TCPP = 4,4′,4″,4‴-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis benzoic acid) particularly exhibited an effective catalytic performance for the heterogeneous oxidation of primary aliphatic alcohols with dioxygen and air without any additives at room temperature. The reaction pathway included the formation of an Ru–oxygen radical intermediate, which was due to the high affinity of diruthenium(II,III) sites for dioxygen.

Room temperature oxidation of alcohols with 1 atm dioxygen and air catalyzed by a novel three-dimensional microporous ruthenium(II,III) 4,4′,4″,4‴-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakisbenzoate tetrafluoroborate

A novel three-dimensional microporous ruthenium (II,III) polymer complex, [ Ru 2 II , III ( H 2 TCPP ) ] BF 4 ( 1) (H 2TCPP = 4,4′,4′,4‴-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis benzoic acid) was synthesized and characterized by elemental analysis, TG/DTA, magnetic susceptibility, FT-IR, diffuse reflectance UV–Vis, ESR, X-ray powder diffraction, BET analysis, and nitrogen and oxygen adsorption measurements. Complex 1 exhibited an effective catalytic performance for the heterogeneous oxidation of various types of alcohols, particularly primary aliphatic alcohols, with molecular oxygen and air without any additives at room temperature.

Novel microporous rhodium(II) carboxylate polymer complexes containing metalloporphyrin: syntheses and catalytic performances in hydrogenation of olefins

Novel microporous rhodium(II) carboxylate polymer complexes containing metalloporphyrin, Rh 2[MTCPP] (M = H 2 1, Cu 2+ 2, Ni 2+ 3, Pd 2+ 4) (H 2TCPP = 4,4′,4″,4′″-(21 H,23 H-porphine-5,10,15,20-tetrayl)tetrakis benzoic acid), were synthesized and completely characterized by elemental analysis, TG/DTA, magnetic susceptibilities, FT-IR, DR-UV–vis, XRPD, BET analysis, and nitrogen adsorption measurements. These complexes possess carboxylate bridged dinuclear rhodium(II) sites and mononuclear copper(II), nickel(II), and palladium(II) centers in the porphyrin ring that form uniform micropores of ca. 5.0 Å. Furthermore, they show high surface areas and high nitrogen adsorption capacities and act as efficient heterogeneous catalysts for the hydrogenation of olefins at approximately 200 K. The unique bimetallic effects shown by metalloporphyrin and dinuclear rhodium sites in micropores were investigated by kinetic studies and hydrogen and propene adsorption–desorption measurements; the priority coordination of olefins onto metalloporphyrins and the intramolecular transfer of hydrogen from a rhodium center to a olefin molecule coordinated onto metalloporphyrin remarkably reflects the catalytic activities in hydrogenation.

Molecular‐Level Design of Efficient Microporous Materials Containing Metal Carboxylates: Inclusion Complex Formation with Organic Polymer, Gas‐Occlusion Properties, and Catalytic Activities for Hydrogenation of Olefins

AbstractFor Abstract see ChemInform Abstract in Full Text.

Photophysical characterization of chosen Ln(III) macromolecular complexes

Spectral characterization of N,N′‐Bis(2,4‐dihydroxobenzylidene)1,2‐diaminobenzene (DHDA) complexes with chosen f‐ and d‐metal ions are described. Physico‐chemical properties of a series of complexes were studied in methanol solution using UV‐VIS, IR and fluorescence spectroscopy. It was found that the excitation and fluorescence spectra of DHDA in water and methanol after being exposed to ultraviolet radiation, show very obvious photochromism. The formation of 1: 1 complexes between 4, 4′, 4″, 4‴‐(porphine‐5,10,15,20‐tetrayl)‐tetrakis benzoic acid, (TCPPH2) and La(III), Eu(III) and Yb(III) in methanolic solution, with the use of the spectrophotometric and spectrofluorimetric methods. The conditional stability constants of the complexes were studied by monitoring the spectral changes of energy and intensity of Q bands of the porphyrin.

Microporous Rhodium(II) 4,4′,4″,4″′-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakisbenzoate. Synthesis, Nitrogen Adsorption Properties, and Catalytic Performance for Hydrogenation of Olefin

Abstract A novel microporous rhodium(II) coordination polymer, [Rh2(H2TCPP)] (1) (H2TCPP = 4,4′,4″,4″′-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis benzoic acid) was synthesized. The complex 1 showed high porosity of the micropores of 7.3 Å. The amount of nitrogen adsorbed by 1 was 2.87 mole per mole of Rh, which is about three times that of rhodium(II) fumarate and rhodium(II) terephthalate. Complex 1 also showed high turnover frequencies for the hydrogenation of ethylene and propene at ca. 200 K.

A novel assembly of cyclodextrins with 4,4′4″,4‴-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis(benzoic acid) through hydrogen bonds

Semi-closed assemblies are formed from cyclodextrins (CyDs) and 4,4′,4″,4‴-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis benzoic acid (PTTKBA); the assemblies are a new group of host molecules that possess inclusion properties different from those of the component CyDs.