Structurally influenced optical nonlinearities and ultrafast dynamics in β-acroleyl- and β-dicyanobutadienyl-appended cobalt corroles

The strong two-photon induced nonlinear absorption and self-focusing type positive nonlinear refraction are pronounced by the structural engineering in β-functionalized cobalt corroles.

Effect of ivermectin, amitraz and fipronil on midgut epithelium and digestive enzyme profile in Rhipicephalus microplus ticks (Acari: Ixodidae)

Blood feeding and digestion are vital physiological activities essential for the survival and reproduction of ticks. Chemical acaricides viz., ivermectin, amitraz and fipronil, are known to act on the central nervous system, resulting in the mortality of ticks. The present study is focused on the effect of these acaricides on the midgut and gut enzymes of Rhipicephalus microplus. The ultra-thin sections of midgut of ivermectin-treated ticks showed irregular basal membrane and ruptured digestive vesicles. Amitraz treatment resulted in a notable decrease in digestive cells with pleats in the basal membrane, while fipronil-exposed ticks exhibited reduced digestive cells, loss of cellular integrity, and disintegration of the basal membrane and muscle layer. The gut tissue homogenate of ivermectin and fipronil treated ticks showed a significant reduction of cathepsin D level, 76.54 ± 3.20 μg/mL and 92.67 ± 3.72 μg/mL, respectively, as compared to the control group (150.0 ± 3.80 μg/mL). The leucine aminopeptidase level (4.27 ± 0.08 units/mL) was significantly decreased in the ivermectin treated ticks compared to other treatment groups. The acid phosphatase activity (29.16 ± 0.67 μmole/min/L) was reduced in the ivermectin treated group whereas, increased activity was observed in the fipronil and amitraz treated groups. All the treatment groups revealed increased alkaline phosphatase levels (17.47-26.72 μmole/min/L). The present finding suggests that in addition to the established mechanism of action of the tested acaricides on the nervous system, the alterations in the cellular profile of digestive cells and enzymes possibly affect the blood digestion process and thus the synthesis of vital proteins which are essential for vitellogenesis, and egg production in ticks.

Third-order nonlinear optical properties of highly electron deficient, nonplanar push-pull porphyrins: β-nitro-hexa-substituted porphyrins bearing bromo, phenyl, and phenylethynyl groups

β-Heptasubstituted porphyrins [MTPP(NO2)X6; M = 2H, NiII, CuII, and ZnII; X = Br, Ph, and PE] were synthesized and their third-order nonlinear optical (NLO) properties explored using the single-beam Z-scan technique with femtosecond, MHz pulses in the visible range. The three-photon absorption (γ), third-order nonlinear optical susceptibility (χ3), three-photon absorption cross-section (σ3), and nonlinear refractive index (n2) have been determined from theoretical fits with experimental results. The sign and magnitude of the nonlinear refractive index (n2) have been obtained from the closed-aperture experiment while the three-photon absorption coefficient and three-photon absorption cross-section were determined from the open-aperture experiment. The magnitudes of the 3PA and σ3 extended in the range of (2.7-3.4) × 10-23 cm3 W-2 and (5.5-7.0) × 10-78 cm6 s2, respectively. The higher magnitude of the NLO coefficients ensures their utility in optical and photonic applications.

π-Extended nonplanar cobalt porphyrins immobilized on MWCNTs as efficient electrocatalysts for selective oxygen reduction reaction

Two π-extended cobalt porphyrins are synthesized and one of them is crystallographically characterized. The nanocomposites of nonplanar (curved) porphyrin immobilized multi-walled carbon nanotubes were thoroughly characterized spectroscopically and microscopically, showing ∼200 mV positive shift in the O2 reduction peak potential in aqueous media and ∼100 mV shift in the onset potential of the O2 reduction relative to the control meso-tetraphenylporphyrinatocobalt(II) nanocomposite. Both the π-extended cobalt porphyrin immobilized nanocomposites efficiently catalyze selective 4e-/4H+ O2 reduction under ambient conditions with excellent methanol tolerance and high stability due to effective π-π interactions, and could be an alternative for expensive Pt-based cathode materials in fuel cells.

Insights into the mechanism of binding of doxorubicin and a chlorin compound with 22-mer c-Myc G quadruplex

BACKGROUND

The interaction of small molecules with G quadruplexes is in focus due to its role in molecular recognition and therapeutic drug design. Stabilization of G-quadruplex structures in the promoter regions of oncogenes by small molecule binding has been demonstrated as a potential approach for cancer therapy.

METHODS

In this study, electronic spectroscopy (ultraviolet-visible, fluorescence, circular dichroism), differential scanning calorimetry, and molecular modeling were employed to explore the interactions between the chemotherapy drug doxorubicin and a chlorin compound 5,10,15,20-tetraphenyl-[2,3]-[bis(carboxy)-methano]chlorin (H2TPC(DAC)), and the c-Myc 22-mer G quadruplex DNA.

RESULTS

Spectroscopic studies indicated external binding of the compounds with partial stacking at the end quartets. Calorimetric studies and temperature dependent circular dichroism data displayed increased melting temperatures of G quadruplex structure on binding with the compounds. Circular dichroism spectra indicated that the G quadruplex structure is intact upon ligand binding. Both the compounds showed binding affinities of the order of 106 M-1. Fluorescence lifetime studies revealed static quenching as major mechanism for fluorescence quenching. Polymerase chain reaction stop assay hinted that binding of both ligands under study could inhibit the amplification of the DNA sequence.

CONCLUSION

Results show that doxorubicin and H2TPC(DAC) bind to the 22-mer c-Myc quadruplex structure with good affinity and induce stability.

SIGNIFICANCE

Doxorubicin and H2TPC(DAC) have demonstrated their affinity towards c-Myc G quadruplex DNA, stabilizing it and inhibiting expression and polymerization. The results can be of practical use in designing new analogs for the two compounds, which can become potent anti-cancer agents targeting the c-Myc GQ structure.

Panchromatic and Perturbed Absorption Spectral Features and Multiredox Properties of Dicyanovinyl- and Dicyanobutadienyl-Appended Cobalt Corroles

Four new β-functionalized π-extended cobalt corroles with one and two dicyanovinyl (DCV) or dicyanobutadienyl (DCBD) moieties at the 3- and 3,17-positions have been synthesized and characterized by various spectroscopic techniques. Interestingly, the synthesized DCV- and DCBD-appended cobalt corroles displayed panchromatic and near-infrared absorption in the range 300-1100 nm in CH2Cl2 and pyridine solvents. (MN)2-(Cor)Co and A2MN2-(Cor)Co exhibited 8-9 times enhancement in the molar absorptivity of the Q band compared to the parent corrole ((Cor)Co). The unique absorption spectral features of these β-functionalized cobalt corroles are splitting, broadening, and red-shifting in the Soret and Q bands. One DCV unit brings a 30-46 nm red shift, whereas one DCBD unit brings a 40-75 nm red shift in the Q band compared to the corresponding precursors. This is rare that the intensity of the longest Q band is greater than or equal to the Soret-like bands. These corrole derivatives exhibit UV-vis spectral features similar to those of chlorophyll a. A 220 mV positive shift per DCV group and 160 mV positive shift per DCBD group were observed in the first oxidation potentials compared to (Cor)Co in the desired direction for the utility of these cobalt complexes in electrocatalysis. DFT studies revealed that HOMO and LUMO were stabilized after appending DCV and DCBD groups on the corrole macrocycle and exhibited a "push-pull" behavior leading to promising material applications in nonlinear optics (NLO) and catalysis.

First report of molecular confirmation and phylogenetic analysis of ocular seteriasis in buffalo in India using 12S rRNA

An adult Indian buffalo (Bubalus bubalis) presented with corneal opacity, irritation, and excessive lacrimation from the left eye in the Referral Veterinary Polyclinic-Teaching Veterinary Clinical Complex (RVC-TVCC), Indian Veterinary Research Institute, Izatnagar. Clinical examination revealed a whitish thread-like worm in the left eye's anterior chamber. The worm was surgically removed from the eye with supportive nerve blocks. Light microscopy was used for parasite morphological identification, which provided insight into the worm as female Setaria sp. Genomic DNA was isolated, and polymerase chain reaction amplification of 12S rRNA was conducted for molecular confirmation of the parasite. The amplicon was sequenced and analysed by bioinformatics software. Sequence data showed an amplicon size of 243 bp. Phylogenetic analysis with reference data from the NCBI Genbank database revealed the worm was S. digitata, with a similarity of 99.17%. The common predilection site of S. digitata is in the peritoneal cavity of natural hosts like cattle and buffalo and is mostly non-pathogenic. The aberrant migration of the parasite larva to the brain and eye commonly occurs in goats, sheep, and horses, causing clinical conditions like cerebrospinal nematodiasis (lumbar paralysis) and ocular setariasis, respectively. Nevertheless, until now, there have been no reports of ocular setariasis in buffalo. This report is the first unusual occurrence of ocular setariasis in buffalo and its molecular confirmation and phylogenetic analysis using 12S rRNA.

Enhanced Femtosecond Nonlinearities and Multiphoton Absorptions in Discrete Bands of Porphyrins

Optical nonlinearities of discrete absorption energy levels of one of the typical heterocyclic aromatic molecules, free-base porphyrins, have been probed over a broad spectral region (400-1600 nm) utilizing intense femtosecond pulses. A wide range of strong one- and multiphoton-induced nonlinear absorptions of both the blue-end Soret (B) band (au → b1g) and red-end orbital mixing split quasi-allowed Q-bands (Qx(0,0; 0,1), Qy(0,0; 0,1), au → eg) are critically probed and reported. During the resonant excitation within B- (400 nm) and Q-bands (600-750 nm), the nonlinear absorption has become predominant by the saturation of absorption (SA) of the one-photon absorption (1PA) process due to ground-state bleaching. At nonresonant wavelengths, it is dominated by the reverse saturation of absorption (RSA), involving various nonlinear processes of two-, three-, and four-photon (2PA, 3PA, and 4PA) absorptions, either to B- or Q-bands (1100-1600 nm). The laser intensity-dependent nonresonant (2PA, 800 nm) excitations for the prominent B-band show a distinct cross-over from SA to RSA, contributed by the excited-state absorption (ESA) utilizing a three-photon induced (3PA) process, whereas resonant (1PA, 400 nm) excitation reveals a systematic strong SA process. Both wavelength- and intensity-dependent nonlinear refractive index studies exhibit positive electronic Kerr-based self-focusing effects, with prominent contributions of nonlinear absorption and higher-order effects. The spectrally discrete, highly intense laser probing of individual energy bands and the consequent variety of nonlinearities can be broadly generalized for many free-base porphyrins and metalloporphyrins. The present studies provide a strong foundation and new insight into the broad categories of macrocycles, such as porphyrins and phthalocyanines, for myriad applications in nonlinear optics and bio/optophotonics.

Co(II) Porphyrin-MWCNT Nanoconjugate as an Efficient and Durable Electrocatalyst for Oxygen Reduction Reaction

Recently, researchers are seeking alternatives to replace Pt-based oxygen reduction reaction (ORR) catalysts used in fuel cells due to their high cost and certain stability and selectivity issues. For this purpose, we have synthesized a nanoconjugate, cobalt(II) porphyrin (5,10,15-triphenyl-20-(4-aminophenyl)porphyrinatocobalt(II), CoTPP-NH₂) covalently attached to the acid-functionalized multiwalled carbon nanotubes and characterized by various techniques including UV-vis spectroscopy, FTIR, TGA, FESEM, TEM, and Raman spectroscopy. The oxygen reduction performance of the nanoconjugate is checked in basic medium. The ORR onset potential of the nanoconjugate-modified electrode is nearly the same as that of the state-of-the-art platinum-carbon electrode and stable for more than 3000 CV cycles with a 20 mV difference in the onset potential before and after the 3000 CV cycles. The above extrapolations reveal that the nanoconjugate has efficient performance for the ORR in basic medium.

Synthesis, Spectral, Redox, and Sensing Studies of β-Dicyanovinyl-Appended Corroles and Their Metal Complexes

A new family of β-dicyanovinyl (DCV)-appended corroles represented as MTPC(MN) (where M = 3H, Cu, Ag, and Co(PPh₃) and MN = malononitrile and TPC = 5,10,15-triphenylcorrole) were synthesized starting from the free base mono β-formyl corrole, H₃TPC(CHO), and characterized along with their respective MTPC(CHO) and MTPC complexes as to their spectroscopic and electrochemical properties in nonaqueous media. Comparisons between the two series of corroles demonstrate a pronounced substituent effect of the β-DCV group on the physicochemical properties making the MTPC(MN) derivatives substantially easier to reduce and more difficult to oxidize than the formyl or unsubstituted corroles. In addition, the colorimetric and spectral detection of 11 different anions (X) in the form of tetrabutylammonium salts (TBAX, X = PF₆^-, OAc^-, H₂PO₄^-, CN^-, HSO₄^-, NO₃^-, ClO₄^-, F^-, Cl^-, Br^-, and I^-) were also investigated in nonaqueous media. Of the investigated anions, only CN^- was found to induce changes in the UV-vis and ¹H NMR spectra of the β-DCV metallocorroles. This data revealed that CuTPC(MN) and AgTPC(MN) act as chemodosimeters for selective cyanide ion detection via a nucleophilic attack at the vinylic carbon of the DCV substituent, while (PPh₃)CoTPC(MN) acts as a chemosensor for cyanide ion sensing via axial coordination to the cobalt metal center. A low-limit detection of cyanide ions was observed at 1.69 ppm for CuTPC(MN) and 1.17 ppm for AgTPC(MN) in toluene.

Symmetrically Functionalized Copper and Silver Corrole-Bis-Tetracyanobutadiene Push-Pull Conjugates: Efficient Population of Triplet States via Charge Transfer

Copper and silver tritolylcorroles (TTC) are symmetrically functionalized to carry two tetracyanobutadiene (TCBD) entities via [2+2] cycloaddition-retroeletrocyclization reaction involving functionalized corroles with an electron acceptor, tetracyanoethylene (TCNE) in excellent yields, as the first examples of corrole-TCBD push-pull systems. The strong push-pull effect resulted in charge polarization in the ground state resulting in a considerable hypsochromic shift, extending the absorption into the near-IR region. Electrochemical and computational studies revealed interactions between the TCBD entities via the corrole π-system and the degree of such interactions was found to depend on the metal ion present in the corrole cavity. Energy considerations suggested charge transfer (CT) from the S2 or vibrationally hot S1 state but not the relaxed S1 state in the case of CuTTC(TCBD)2 while CT to occur from all these states in the case of AgTTC(TCBD)2. Additionally, the high-energy CT states populate the low-lying triplet states. Systematic femtosecond pump-probe studies provided the ultimate proof for the occurrence of excited CT as a function of excitation wavelength followed by the efficient population of the triplet states. The present study brings out the significance of charge transfer in efficiently populating the triplet states in rather unusual copper and silver corroles carrying two TCBD entities.

Oxido-Molybdenum(V) Corroles as Robust Catalysts for Oxidative Bromination and Selective Epoxidation Reactions in Aqueous Media under Mild Conditions

Two new meso-substituted oxido-molybdenum corroles were synthesized and characterized by various spectroscopic techniques. In the thermogram, MoO[TTC] (1) exhibited excellent thermal stability up to 491 °C while MoO[TNPC] (2) exhibited good stability up to 318 °C. The oxidation states of the molybdenum(V) were verified by electron paramagnetic resonance (EPR) spectroscopy and exhibited an axial compression with d_xy¹ configuration. Oxido-molybdenum(V) complexes were utilized for the selective epoxidation of various olefins with high TOF values (2066-3287 h^-1) in good yields in a CH₃CN/H₂O (3:2, v/v) mixture in the presence of hydrogen peroxide as a green oxidant and NaHCO₃ as a promoter. The oxidative bromination catalytic activity of oxido-molybdenum(V) complexes in an aqueous medium has been reported for the first time. Surprisingly, MoO[TNPC] (2) biomimics of the vanadium bromoperoxidase (VBPO) enzyme activity exhibited remarkably high TOF values (36 988-61 646 h^-1) for the selective oxidative bromination of p-cresol and other phenol derivatives. Catalyst MoO[TNPC] (2) exhibited higher TOF values and better catalytic activity than catalyst MoO[TTC] (1) due to the presence of electron-withdrawing nitro groups evident from cyclic voltammetric studies.

Monitoring of Harmful Algal Bloom (HAB) of Noctiluca scintillans (Macartney) along the Gulf of Mannar, India using in-situ and satellite observations and its impact on wild and maricultured finfishes

In the Gulf of Mannar, Noctiluca scintillans blooms have been observed three times in September 2019, September and October 2020, and October 2021. It was determined and measured how the bloom period affects ichthyo-diversity. Noctiluca cell density varied slightly from year to year, ranging from1.8433 × 10³ cells/L to 1.3824 x 10⁶cells/L. In surface and sea bottom waters, high ammonia levels and low dissolved oxygen levels were noted. During the bloom period a significant increase in chlorophyll concentration was found. The amount of chlorophyll in GOM was extremely high, according to remote sensing photos made using MODIS-Aqua 4 km data. Acute hypoxia caused the death of wild fish near coral reefs and also in fish reared in sea cages. The decay of the bloom resulted in significant ammonia production, a dramatic drop in the amount of dissolved oxygen in the water, and ultimately stress, shock, and mass mortality of fishes.

Facile Synthesis of β-Tetracyano Vanadyl Porphyrin from Its Tetrabromo Analogue and Its Excellent Catalytic Activity for Bromination and Epoxidation Reactions

Complex 2,3,12,13-tetracyano-5,10,15,20-tetraphenylporphyrinatooxidovanadium(IV) {[V^IVOTPP(CN)₄], 2} has been prepared by nucleophilic substitution of β-bromo groups of the corresponding 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrinatooxidovanadium(IV) {[V^IVOTPP(Br)₄], 1} using CuCN in quinoline. Both complexes show biomimetic catalytic activity similar to enzyme haloperoxidases and efficiently brominate various phenol derivatives in the presence of KBr, H₂O₂, and HClO₄ in the aqueous medium. Between these two complexes, 2 exhibits excellent catalytic activity with high turnover frequency (35.5-43.3 s^-1) due to the strong electron-withdrawing nature of the cyano groups attached at β-positions and its moderate nonplanar structure as compared to 1 (TOF = 22.1-27.4 s^-1). Notably, this is the highest turnover frequency value observed for any porphyrin system. The selective epoxidation of various terminal alkenes using complex 2 has also been carried out, and the results are good, specifying the importance of electron-withdrawing cyano groups. Catalysts 1 and 2 are recyclable, and the catalytic activity proceeds through the corresponding [V^VO(OH)TPP(Br)₄] and [V^VO(OH)TPP(CN)₄] intermediates, respectively.

Ethyl Acetoacetate and Acetylacetone Appended Hexabromo Porphyrins: Synthesis, Spectral, Electrochemical, and Femtosecond Third-Order Nonlinear Optical Studies

Asymmetrically substituted porphyrins possessing ethyl acetoacetate or acetylacetone (EAA or acac) with six bromine atoms at β-positions were synthesized and characterized by various spectroscopic techniques such as UV-Vis, Fluorescence and...

Molecular detection of Coxiella-like endosymbionts in Rhipicephalus microplus from north India

Apart from the tick-borne pathogens affecting human and animal health, ticks also harbor various non-pathogenic endosymbionts with dynamic ecological interactions. These endosymbionts are unexplored from the Indian ticks; hence this pilot study was conducted. Seventy-nine ticks were collected from Nainital district of Uttarakhand state of north India and were identified as Rhipicephalus microplus morphologically and by molecular analysis. PCR and sequence analysis were carried out to detect the presence of Rickettsia-like, Coxiella-like and Francisella-like endosymbionts in these ticks. Based on the partial 16S rRNA gene sequence, Coxiella-like endosymbiont (CLE) was detected in the adult and other life-cycle stages of ticks with 96.6-97.7% nucleotide sequence identity with the published CLE sequences from GenBank. The phylogenetic analysis revealed that the CLE from R. microplus were clustered with the CLE from other Rhipicephalus species. All these CLE formed distinct clades from the pathogenic Coxiella burnetii. None of the tick samples was found positive for Rickettsia-like and Francisella-like endosymbionts in the present study. We also demonstrated the vertical transmission of CLE from surface sterilized and laboratory reared fully engorged adult females to the eggs and the larvae. However, large scale studies are to be conducted to detect various endosymbionts and endosymbiont-tick associations in the Indian tick species and to explore these associations for tick and tick-borne disease control.

Unsymmetrically β-Functionalized π-Extended Porphyrins: Synthesis, Spectral, Electrochemical Redox Properties, and Their Utilization as Efficient Two-Photon Absorbers

Two new series of unsymmetrically β-functionalized porphyrins, MTPP(NO₂)MA (1M), (MA = methyl acrylate) and MTPP(NO₂)MB (2M) (MB = mono-benzo) (where M = 2H, Co(II), Ni(II), Cu(II) and Zn(II)), were synthesized and characterized by various spectroscopic techniques. The saddle shape conformation of ZnTPP(NO₂)MAPy and ZnTPP(NO₂)MB was confirmed by single-crystal X-ray analysis. Density functional theory (DFT) calculation revealed that NiTPP(NO₂)MB has a severe nonplanar geometry possessing a high magnitude of ΔC_β = ±0.727 Å and Δ24 = ±0.422 Å values among all other porphyrins. Synthesized β-substituted porphyrins exhibited red-shifted B- and Q-bands corresponding to their parent molecule due to the electron-withdrawing peripheral substituents. Notable redshift (Δλ_max = 50-60 nm) in electronic spectral features and with weak-intensity emission spectral features were observed for the free-base porphyrins and Zn(II) complexes compared to H₂TPP and ZnTPP, respectively. The first-ring reduction potential of MTPP(NO₂)MA (1M) exhibited 0.21-0.5 V anodic shift, whereas 0.18-0.23 V anodic shift was observed in the first-ring oxidation potential compared to the corresponding MTPPs due to the presence of electron-withdrawing β-substituents at the periphery of the macrocycle. Interestingly, NiTPP(NO₂)MA (1Ni) has shown an additional Ni^II/Ni^III oxidation potential observed at 2.05 V along with two ring-centered oxidations. The first-ring reduction and oxidation potentials of MTPP(NO₂)MB (2M) have shown 0.39-0.46 and 0.19-0.27 V anodic shifts with respect to their corresponding MTPPs. The nonlinear optical (NLO) properties of all of the porphyrins were investigated, and the extracted nonlinear optical parameters revealed intense reverse-saturable absorption (RSA) behavior and the self-focusing behavior with positive nonlinear refractive index in the range of (0.19-1.75) × 10^-17 m²/W. Zn(II) complexes exhibited the highest two-photon absorption coefficient (β) and cross section (σ_TPA) of ∼95 × 10^-12 m/W and 19.66 × 10⁴ GM, respectively, among all of the metal complexes.

Synthesis and the spectral, electrochemical, and nonlinear optical properties of β-dicyanovinyl-appended 'push-pull' porphyrins

A series of "push-pull" porphyrins, MTPP(MN)(TPA)₂ (M = 2H, Cu^II, Ni^II, and Zn^II), having triphenylamine (TPA) and dicyanovinyl (DCN) groups at antipodal positions were synthesized and characterised by UV-Vis, fluorescence and NMR spectroscopic techniques, MALDI-TOF mass spectrometry, cyclic voltammetry, DFT, and elemental analysis, which were then further utilized for third-order nonlinear optical measurements under mild conditions using femtosecond laser pulses. Remarkably, MTPP(MN)(TPA)₂ (M = 2H, Cu^II, Ni^II, and Zn^II) exhibited 21-48 nm and 38-80 nm bathochromic shifts in B and Q_x(0,0) bands as compared to the corresponding MTPPs (M = 2H, Cu^II, Ni^II, and Zn^II); the results are consistent with the effect of enhanced resonance due to TPA and -I effect of DCN moieties. In cyclic voltammetry, the push-pull porphyrins exhibited a cathodic shift (0.13-0.51 V) in their first oxidation potential as compared to the precursor owing to the presence of electron-donating TPA groups. The third-order nonlinear optical responses were recorded using a single-beam femtosecond Z-scan technique to retrieve information about the nonlinear absorption and nonlinear refraction of the samples. The two-photon absorption coefficients (β) are in the range of 0.87 × 10^-13 to 4.28 × 10^-13 m W^-1 and the nonlinear refractive index (n₂) in the range of 1.21 × 10^-19 to 7.36 × 10^-19 m² W^-1. The ultrafast absorption dynamics of the ground-state bleaching (GSB) and photo-induced absorption (PIA) are monitored by femtosecond broadband transient absorption studies. The strong nonlinearity of these push-pull porphyrins makes them potential candidates for nonlinear optical and photonic device applications.

Efficient charge transfer from organometal lead halide perovskite nanocrystals to free base meso-tetraphenylporphyrins

The efficient charge transfer from methylammonium lead halide, MAPbX₃ (X = Br, I), perovskite nanocrystals (PNCs) to 5,10,15,20-tetraphenylporphyrin (TPP) molecules has been investigated in detail. The hydrophobically-capped MAPbX₃ PNCs exhibited bright fluorescence in the solution state. However, in the presence of TPP, the fluorescence intensity was quenched, which is ascribed to the electron transfer from the PNCs to TPP. Photoluminescence (PL) spectroscopy and absolute quantum yield measurements were used to evaluate the fluorescence quenching. This efficient fluorescence quenching leads to an increase in the quenching efficiency value. The quenching of fluorescence intensity is not attributed to the change in lifetime, as evidenced by time-correlated single-photon counting (TCSPC) measurements, suggesting a static electron transfer from the PNCs to TPP molecules. Such a static fluorescence quenching corresponds to the adsorption of TPP onto the surface of hydrophobic PNCs, and has been examined via transmission electron microscopy (TEM). Cyclic voltammetry (CV) studies were used to compare the PNCs and PNCs@TPP nanocomposites, revealing that the electron transfer process takes place from the PNCs to the organic acceptor TPP molecules.

Selective epoxidation of olefins by vanadylporphyrin [VIVO(TPP)] and electron deficient nonplanar β-octabromovanadylporphyrin [VIVO(TPPBr8)]

Meso-tetraphenylporphyrinatooxidovanadium(IV) [VIVO(TPP)] (1) and 2,3,7,8,12,13, 17,18-octabromo-meso-tetraphenylporphyrinatooxidovanadium(IV) [VIVO(TPPBr[Formula: see text]] (2) were synthesized and characterized by various spectroscopic techniques. 1 and 2 were utilized as efficient catalysts for the selective epoxidation of olefins. Catalyst 2 shows very high catalytic activity (TOF = 8783–13108 h[Formula: see text] as compared to 1 (TOF = 2175–3296 h[Formula: see text]. The catalysts are recyclable, as their recyclability was checked for four cycles and show only minor reduction of their efficiency.

β-Tetracyanobutadiene-Appended Porphyrins: Facile Synthesis, Spectral and Electrochemical Redox Properties, and Their Utilization as Excellent Optical Limiters

A series of β-TCBD (1,1,4,4-tetracyano-buta-1,3-diene)-appended porphyrins, M-TCBD (M = 2H, Co(II), Ni(II), Cu(II), and Zn(II)), was synthesized from 2,3-diphenylethynyl-12-nitro-meso-tetraphenylporphyrin, H₂-PE₂, and characterized by various spectroscopic techniques and electrochemical studies. The reaction proceeds via [2 + 2] cycloaddition and retroelectrocyclization reactions of tetracyanoethylene (TCNE) with H₂-PE₂. The observed unusual reduction potentials in the cyclic voltammograms of the synthesized porphyrins in the range of -0.06 to -0.10 V are the consequence of the TCBD moiety present at the β-position of the porphyrin macrocycle. Notably, these porphyrins exhibited three porphyrin ring-centered reductions due to extended π-conjugation. The higher nonlinear optical response exhibited by the M-TCBD series as compared to the precursor (H₂-PE₂) was attributed to the existence of intramolecular charge transfer and enhanced polarization in the M-TCBD series. The single-beam femtosecond Z-scan measurements were performed to elucidate the third-order nonlinear optical properties, and the temporal response of these porphyrin molecules was investigated using optical pump-probe spectroscopy to study the excited state absorption dynamics. Z-scan measurements revealed that Co-TCBD exhibited a higher nonlinear optical response as compared to free base porphyrins. The two-photon absorption coefficient (β) and the imaginary part of third-order nonlinear optical susceptibility (χ⁽³⁾) were obtained from the open aperture experiment, whereas the close aperture experiment delivered the magnitude and the sign of the nonlinear refractive index (n₂) and the real part of χ⁽³⁾. Furthermore, the femtosecond transient absorption spectroscopy revealed a faster relaxation dynamics of various absorption processes in a picosecond timescale. The excellent optical limiting threshold (1.90-2.33 × 10¹⁵ W/m²) of the synthesized porphyrins makes them good materials for laser protection and high-power laser operation.

Nickel(II) monobenzoporphyrins and chlorins: synthesis, electrochemistry and anion sensing properties

A series of nickel(II) monobenzochlorins (MBCs) and monobenzoporphyrins (MBPs) containing β-appended or meso,β-fused indanedione (IND) or malononitrile (MN) groups were synthesized and characterized for their physicochemical, electrochemical and anion sensing properties. Each investigated compound contained four meso-phenyl rings and a single β,β'-fused 4,5-di(methoxycarbonyl)benzene ring, with the chlorins represented as NiMBC(Y)₂(R)₄ and the porphyrins as NiMBP(Y^F)₂, where Y is an indanedione (IND) or malononitrile (MN) group, R = H or Br and Y^F is a meso,β-fused IND or MN substituent. One of the investigated compounds, NiMBP(IND)₂, was structurally characterized and shown to possess a ruffled macrocyclic conformation. The monobenzochlorins, NiMBC(IND)₂, NiMBC(IND)₂Br₄ and NiMBC(MN)₂, reversibly respond to basic anions such as CN^-, F^-, OAc^- and H₂PO₄^- through a visible color change assigned to the deprotonation of the vicinal proton on the appended IND or MN substituents. The malononitrile-fused Ni^II monobenzoporphyrin, NiMBP(MN)₂, exhibited a selective but irreversible visual detection of cyanide ions (LOD = 2.23 ppm). This reaction afforded a tri-fused π-extended monobenzoporphyrin product represented as NiMBP(VCN)₂ (where VCN = meso,β-fused vinyl cyanide) in non-aqueous media and proceeded via anion induced electron transfer (AIET). The in situ generated π-extended porphyrin was also isolated and characterized as to its physicochemical and electrochemical properties and found to possess a narrow electrochemical HOMO-LUMO gap of 1.46 V along with a near-IR (NIR) absorption band located at 861 nm.

Buoyant Convective Flow and Heat Dissipation of Cu–H2O Nanoliquids in an Annulus Through a Thin Baffle

This article numerically investigates the buoyant convective flow and thermal transport enhancement of Cu–H2O nanoliquid in a differentially heated upright annulus having a thin baffle. For the analysis, the outer and inner cylinders are cooled and heated respectively through insulated top and lower boundaries. Also, the baffle temperature is assumed to be that of the hot cylinder. The finite difference based numerical technique is used to solve the system of equations governing the physical processes. The findings are accessible in terms isotherms, streamlines and Nu number for wider ranges of baffle positions and lengths, Rayleigh numbers, and by considering different nanofluid (NF) volume fractions. The average Nu number is enhanced in addition of the Cu nanoparticle to the base liquid and it is also found the liquid flow and heat transport can be successfully controlled via the appropriate selection of baffle location and length. Principally, the baffle length having 20% of annular width placed at 80% of the annular height has been found to produce higher thermal transport rates as compared to other choices of baffle lengths and positions.

Strong two-photon absorption and ultrafast dynamics of meso-functionalized "push-pull"trans-A2BC porphyrins

A new series of "push-pull"meso-substituted trans-A₂BC porphyrins, where A = mesityl, B = phenothiazine (push) and C = o/p-nitrophenyl moiety (pull) and M = 2H, Ni(ii), Cu(ii), and Zn(ii), were synthesized. These trans-A₂BC porphyrins were characterized by various techniques viz. UV-Vis, fluorescence and NMR spectroscopy, matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, cyclic voltammetry, single-crystal X-ray diffraction analysis and density functional theory (DFT) studies. The single crystal structure of the newly synthesized free base trans-H₂A₂BC porphyrin (2) revealed the orientation of meso-substituents and the planar conformation of the porphyrin core. All newly synthesized free base trans-H₂A₂BC porphyrins (1 or 2) and their metal complexes exhibited a sharp Soret band. The first reduction potential of all synthesized trans-MA₂BC porphyrins showed an anodic shift as compared with that of meso-tetraphenylporphyrins (MTPPs) due to the strong electron withdrawing nature of the nitrophenyl group. In general, the first oxidation potential of trans-MA₂BC porphyrins shows a cathodic shift due to the electron donating phenothiazine moiety as compared to that of MTPPs. p-Nitrophenyl appended trans-A₂BC porphyrins exhibited large ground state dipole moment values (8.59-9.64 D) as compared to MTPPs (0.0013-0.052 D) owing to the polarized "push-pull" effect of meso-substituents such as phenothiazine (push) and nitrophenyl (pull) moieties. Femtosecond nonlinear optical (NLO) studies performed with kHz pulses at 800 nm revealed strong two-photon absorption coefficients (∼0.082-0.0953 cm GW^-1) and cross-sections (∼1.71-1.95 × 10³ GM) for these "push-pull" porphyrins. We have also attempted to understand the NLO coefficients in terms of the structural changes in these porphyrin derivatives. A comparison that has been accomplished with similar porphyrin molecules and under similar experimental conditions revealed the superior performance of the title molecules. Furthermore, femtosecond transient absorption studies demonstrated several ultrafast processes from various excited states in these porphyrins, useful for identifying the processes relevant to optical switching applications.

β-Disubstituted silver(III) corroles: Facile synthesis, photophysical and electrochemical redox properties

Facile synthesis of 3,17-disubstituted Ag(III) tritolylcorroles (2-5), R2[TTC]Ag where R = methyl (2), phenyl (3), methyl acrylate (MA) (4) and phenylethynyl (PE) (5) using Pd-catalyzed reactions in good to excellent yields are reported. All synthesized corroles were characterized by various spectroscopic techniques and mass spectrometry. MA2[TTC]Ag (4) and PE2[TTC]Ag (5) exhibited highly red-shifted electronic spectral bands with considerable broadening due to extended [Formula: see text]-conjugation and electron withdrawing effect of [Formula: see text]-substituents. Geometry optimization of these corroles was performed using density functional theory (DFT). Among all, MA2[TTC]Ag (4) exhibited very high dipole moment (10.31 D) which could be the potential candidate for nonlinear optical (NLO) applications. The redox tunability was achieved by substituting electron donating and withdrawing substituents at the [Formula: see text]-positions. Particularly, corroles 4 and 5 exhibited lower HOMO–LUMO gap due to extended [Formula: see text]-conjugation and electron withdrawing [Formula: see text]-substituents.

Molecular and serological detection of Anaplasma infection in carrier cattle in north India

Anaplasma marginale infection in cattle (n = 216) in the states of Uttar Pradesh and Uttarakhand, North India was screened by microscopy and nested-polymerase chain reaction (PCR). Two recombinant proteins viz. major surface protein (MSP) 5 and MSP2 of A. marginale were expressed in Escherichia coli and their potential in the detection of antibodies to Anaplasma species in the cattle was evaluated by immunoglobulin G-enzyme linked immunosorbent assay (IgG-ELISA). The MSP5 IgG ELISA results were compared with competitive (c) inhibition ELISA. Microscopy being the least sensitive diagnostic test detected 12.0% of animals positive for A. marginale infection while nested-PCR detected 87.9% of these animals as positive for A. marginale infection. The recombinant MSP5 antigen showed positive reactivity in 170/190 nested-PCR confirmed positive animals (sensitivity 89.5%) with specificity of 77.0%. In comparison, the recombinant MSP2 antigen showed lesser sensitivity and specificity of 79.0% and 69.2%, respectively. The cELISA was more sensitive and specific than IgG-ELISA. However, molecular detection by msp5 nested-PCR was highly sensitive and reliable for detection of carrier cattle for Anaplasma infection. The study indicated that a large cattle population (87.9%) was carrier for A. marginale infection in this region of the country.

Highly efficient Co(II) porphyrin catalysts for the extractive oxidative desulfurization of dibenzothiophene in fuel oils under mild conditions

Co(II) porphyrins have been utilized as efficient and selective catalysts for the extractive oxidative desulfurization reaction on the refractory dibenzothiophene (DBT) in [Formula: see text]-dodecane (model middle distillate fuel oil). The acetonitrile was taken as extracting polar solvent and H2O2 was used as oxidant. The reaction optimization was done with respect to DBT:catalyst molar ratio; DBT:H2O2 molar ratio; extracting solvent: CH3CN/[Formula: see text]-dodecane volume ratio; reaction temperature and time. Under the optimized conditions, a maximum of [Formula: see text]98% DBT removal was achieved by using the meso-tetrakis(4[Formula: see text] methoxyphenyl)porphyrinatocobalt(II) as catalyst under mild conditions at 50[Formula: see text]C.

Fused Nickel(II) Porphyrins-Sensing of Toxic Anions and Selected Metal Ions Through Supramolecular Interactions

Ni(II) porphyrins having fused -NH group were synthesized and characterized by various spectroscopic techniques. The fused porphyrins 1 and 2 were used to detect species of opposite polarity. 1 was used to sense toxic anions viz. cyanide and fluoride ions whereas 2 was used for detecting some selective metal ions including toxic mercury(II) ions. 1 is having acidic -NH proton, which detects anions via hydrogen bonding interactions followed by anion-induced deprotonation. On the other hand, 2 senses the metal species via weak charge transfer interactions from oxygen atom of the formyl group to the added metal ions. The limit of detection was calculated in case of 1 as 2.13 and 3.15 ppm for cyanide and fluoride ions, respectively. Similarly, the detection limit was found to be 0.930, 2.231, and 0.718 ppm for Cu(II), Fe(III), and Hg(II) ions, respectively, for probe 2. The probes were recovered and reused for several cycles.

Facile Heterogeneous and Homogeneous Anion Induced Electrosynthesis: An Efficient Method for Obtaining π-Extended Porphyrins

Two closely related electrosynthetic approaches are applied for the preparation of novel π-extended tetraphenylporphyrins from malononitrile-appended meso-β di-fused porphyrins, represented as MTPP(MN)₂, where TPP = the dianion of tetraphenylporphyrin and MN = malononitrile. The first method involves application of a controlled reducing potential at a platinum electrode in CH₂Cl₂, while the second proceeds via cyanide anion induced electron transfer. Both methods produced the same decyanated, π-extended di-fused porphyrins represented as MTPP(VCN)₂ where VCN = vinyl cyanide and M = H₂, Ni^II, Cu^II, or Zn^II in almost quantitative yields. The final isolated and purified porphyrin products are characterized by a split Soret band ranging from 411-497 nm and two broad intense Q bands. The new π-extended porphyrins are easier to reduce than the parent MTPP or MTPP(MN)₂ compounds by 760-800 mV and 180-190 mV, respectively, and possess an electrochemical HOMO-LUMO gap ranging from 1.48 to 1.66 V. They are also characterized by two reversible one-electron ring-centered reductions in CH₂Cl₂ and three reversible one-electron ring-centered reductions in THF. A fourth irreversible reduction is seen in THF at more negative potentials and is assigned to one or two of the fused cyanobenzene rings of the macrocycle.

A dual colorimetric chemosensor for Hg(ii) and cyanide ions in aqueous media based on a nitrobenzoxadiazole (NBD)-antipyrine conjugate with INHIBIT logic gate behaviour

In this work, we have synthesized nitrobenzoxadiazole-antipyrine conjugate 1 from chloro substituted nitrobenzoxadiazole (NBD) with 4-aminoantipyrine by an elegant method which provides good yield and it is characterized by various spectroscopic techniques. The sensing ability of compound 1 is analyzed with the addition of different metal ions and anions in an aqueous methanol medium. It shows rapid colorimetric response for Hg²⁺ and CN^- ions over a wide range of competitive metal ions and anions. On addition of Hg²⁺/CN^- ions, 1 shows a distinct color change from pale yellow to pink and orange red, respectively, thus permitting chemosensor 1 to be used for 'naked eye' detection of Hg²⁺ and CN^- ions. The change in spectral features and color of 1 with the addition of Hg²⁺ and CN^- ions is mainly due to the formation of a charge-transfer complex (1₂-Hg²⁺) and cyanide ion induced deprotonation of 1. The interaction between the Hg²⁺/CN^- ion and 1 is characterized by mass spectrometry and ¹H-NMR spectral titrations. In addition, sensor 1 is reversible and reusable and it can be developed as an INHIBIT type logic gate. Compound 1 detects Hg²⁺ and CN^- ions upto 2.57 × 10^-8 M and 1.67 × 10^-7 M, respectively. Further, compound 1 pre-coated test strips detect Hg²⁺ and CN^- ions and they provide a simple and convenient method for determination of Hg²⁺/CN^- ions.

Effect of fused indanedione (IND) groups and antipodal β-substituents on electrochemical properties of unsymmetrical metalloporphyrins

The interacting effect of fused indanedione (IND) groups and antipodal Br [Formula: see text]-substituents on the electroreduction of free-base and transition metal tetraphenylporphyrins (TPPs) are elucidated through the use of cyclic voltammetry. A systematic study of the reduction potentials for mono- and di-fused derivatives of MTPP(IND)(R)2 and MTPP(IND)2(R)2 where R = Br or H and M = Cu[Formula: see text], Ni[Formula: see text], Zn[Formula: see text] or H2 is carried out in pyridine containing 0.1 M tetrabutylammonium perchlorate (TBAP) as supporting electrolyte and demonstrates how the overall electrochemical properties of these compounds can be tuned by systematic changes in the number of meso-[Formula: see text]fused IND groups on the molecule and the presence or absence of electron-withdrawing Br [Formula: see text]-substituents. Under these solution conditions, two reversible one-electron reductions are seen for H2TPP, while three reversible reductions are obtained for H2TPP(IND) or H2TPP(IND)Br2 and four for H2TPP(IND)2Br2. Multiple reductions also occur for the other investigated mono- and di-fused metalloporphyrins. Plots of measured [Formula: see text] values for the two ring-centered reductions of compounds in a given series vs. the number of fused IND groups are linear and with slopes varying in magnitude between 15 and 230 mV/IND depending upon the product of the electron transfer (anion radical or dianion), the specific central metal ion and the presence or absence of Br substituents on the pyrrole ring opposite the fused IND group(s). It is anticipated that the information from this study can be used for predicting the reduction potentials for yet to be synthesized compounds where a specific redox reactivity is desired.

Persubstituted Triphenylamine Bearing Zinc Porphyrin to Host Endohedral Fullerene, Sc3N@C80: Formation and Excited State Electron Transfer

A persubstituted porphyrin with eight entities of triphenylamines at the β-pyrrole positions of a zinc tetraphenylporphyrin, 1, was newly synthesized and characterized. Due to the severe nonplanar distortion caused by the peripheral, electron rich substituents, the zinc porphyrin was able to comfortably bind a relatively large endohedral fullerene, Sc₃N@C₈₀, to form a new class of donor-acceptor-type host-guest complex. Spectral, computational, and electrochemical studies were systematically performed to evaluate the binding, spatial geometry, and redox properties of the host-guest system. Further, free-energy calculations were performed to seek the thermodynamic feasibility of excited state charge transfer. Finally, transient absorption spectral studies at different time scales were performed to secure evidence and kinetic information on excited state charge transfer leading to the 1^•+:Sc₃N@C₈₀^•- charge separated species. The present unprecedented, highly functionalized material with electron rich substituents carries zinc porphyrin as a photoactive host to large endohedral fullerenes, and its ability to undergo excited state electron transfer opens up new avenues to build photoactive host-guest systems relevant to light energy conversion and optoelectronic applications.

Multiple anthelmintic resistance in gastrointestinal nematodes of Caprines on Mountain Research Centre for Sheep and Goat at Kashmir Valley, India

The study was conducted to evaluate the status of anthelmintic resistance in Gastro-Intestinal Nematodes (GINs) of goats at an organized farm located in Kashmir, as there is no report of resistance against these parasites of goats from this temperate region, although it has been reported worldwide including India. Caprines reared at this farm exhibited reduced efficacy to multiple anthelmintics following treatments with Fenbendazole (FBZ), Closantel and Ivermectin (IVM) in Faecal Egg Count Reduction Test (FECRT). The results suggested that the overall efficacy was highest for IVM at 83.5% and 90.0% on 7^th and 14^th day post-treatment, respectively and least for FBZ at 44.3% and 62.5%, respectively, whereas the corresponding figures for closantel were 68.3% and 86.2%, respectively. The pre-treatment faecal culture revealed Haemonchus contortus, Teladorsagia circumcincta and Trichostrongylus colubriformis as predominant strongyles, however, in post-treatment samples, only H. contortus was observed. Further, the infective larvae were subjected to Allele specific PCR (AS-PCR) for accurate diagnosis of BZ resistance. The AS-PCR revealed 52% of H. contortus were homozygous resistant (rr) and 17% were heterozygous (rS) on day “0” before treatment and 100% homozygous resistant (rr) on 7th day post treatment. In both T. colubriformis and T. circumcincta, 100% population was homozygous susceptible (SS) at day “0” before treatment. The overall frequency of resistant (r) allele for H. contortus was 60.5% and for susceptible allele (s) was 39.5%. For T. colubriformis and T. circumcincta the frequency of susceptible allele (s) was 100%. The survey indicated that the GINs of goats on the farm have developed multiple anthelmintic resistance to FBZ, closantel and IVM and the condition is alarming in the farm. Moreover surveillance studies about status of anthelmintic resistance in other farms (Govternment as well as Private) of Kashmir valley should be carried out at large scale to develop effective and sustainable control strategies against GI Nematodes.

N-Confused Porphyrin - A Unique "Turn-On" Chemosensor for CN- and F- ions and "Turn-Off" Sensor for ClO4 - ions

N-Confused meso-tetrakis(4-carbomethoxyphenyl)porphyrin (1) and its Ni(II) complex (1 a) have been synthesized and utilized for anion sensing studies, and the results are compared with N-confused meso-tetraphenylporphyrin (NCTPP). Anion susceptibilities of 1 and 1 a were investigated using spectroscopic, electrochemical, and DFT studies. Porphyrins 1 and 1 a were able to detect CN^- , F^- , and ClO₄ ^- ions selectively over the tested set of anions even at ppm level. Interestingly, the addition of ClO₄ ^- ions resulted in fluorescence quenching (turn off) whereas the addition of F^- or CN^- resulted in fluorescence enhancement (turn on). Notably, the TFA addition resulted in fluorescence quenching, whereas the fluorescence enhancement was observed while adding TBAOH. The higher association constant (K_a ) values with anions, lower detection limit, and shifts in redox potentials are due to the electron-withdrawing effect of the -COOCH₃ group at the para-position of the meso-phenyl ring. This electron-withdrawing nature is crucial for the higher affinity towards anions. The anion sensing description in this article may not only unveil the built-in nature of N-confused porphyrins, but may also provide a general proposal for the development of novel anion sensors based on porphyrinoids. The electron-deficient porphyrin framework, large polarisable π-system, and anion binding through the outer NH or a combination of the above factors serve as a foundation for N-confused porphyrin to act as an anion sensor.

Meso-Tetrapyrenylporphyrins: Synthesis, structural, spectral, electrochemical properties and Förster energy transfer (FRET) studies

Meso-tetrapyrenylporphyrin and its metal (Co[Formula: see text], Cu[Formula: see text], Ni[Formula: see text] and Zn[Formula: see text]) complexes were synthesized, characterized and studied for their spectral, electrochemical and energy transfer properties. DFT optimization was carried out to gain an insight into the interactions between the porphyrin [Formula: see text]-system and the pyrenyl substituents. The pyrenyl substituents and the porphyrin core remain essentially orthogonal to each other in both the free base and the metallated porphyrins. Redox potentials of the pyrenylporphyrins are marginally shifted as compared to their corresponding phenyl derivatives. Förster resonance energy transfer (FRET) studies were carried out in toluene for free-base pyrenylporphyrin and its Zn(II) complex. Since pyrene is a good donor, an efficient energy transfer from pyrene (D) to the porphyrin core (A) on the order of 80–85% was observed for these two compounds. It was observed that energy transfer occurs mainly via ”through-bond” (TB) interaction rather than ”through-space” (TS) interaction.

Structural, Photophysical, and Electrochemical Properties of Doubly Fused Porphyrins and Related Fused Chlorins

The electrochemical and physicochemical properties of tetraphenylporphyrins and tetraphenylchlorins with two fused indanedione (IND) or malononitrile (MN) groups and two antipodal Br, Ph, or H β-substituents are investigated in nonaqueous media. These compounds were synthesized by oxidative fusion of free-base trans-chlorins, followed by metalation. The corresponding free-base di-fused chlorins were also isolated as intermediates and characterized for comparisons. The examined di-fused porphyrins (DFP) and di-fused chlorins (DFC) are represented as MDFP(Y)₂(R)₂ and H₂DFC(Y)₂(R)₂, where M = 2H, Cu^II, Ni^II, Zn^II, and Co^II, Y is a fused indanedione (IND) or malononitrile group (MN), and R = H, Br, or Ph. The IND- and MN-appended compounds in both series exhibit the expected two one-electron oxidations but quite different redox behavior is observed upon reduction, where the free-base IND-appended chlorins show four reversible one-electron reductions, compared to only two for the related free-base MN-appended chlorins. Although porphyrin trianions and tetraanions have been recently described for derivatives with highly electron-withdrawing and/or π-extending substituents, this seems not to be the case for the doubly fused IND-chlorins, where the first two one-electron additions are proposed to be located at the conjugated macrocycle and the last two at the fused IND groups, each of which is reduced at a different potential, consistent with the behavior expected for two equivalent and interacting redox centers. Unlike the examined chlorins, which are all stable in their electroreduced forms, the electrogenerated anionic forms of the di-fused porphyrins are all highly reactive and characterized by cyclic voltammograms having reduction peaks not only for the synthesized compounds added to solution but also for one or more new redox active species formed at the electrode surface in homogeneous chemical reactions following electron transfer. Comparisons are made between electrochemical behavior of the structurally related porphyrins and chlorins and the sites of electron transfer assigned on the basis of known electrochemical diagnostic criteria. One of the compounds, ZnDFP(MN)₂, was also structurally characterized as having a ruffled and twisted macrocyclic conformation.

Unsymmetrical β-functionalized ‘push–pull’ porphyrins: synthesis and photophysical, electrochemical and nonlinear optical properties

A new family of unsymmetrical β-TPA appended ‘push–pull’ porphyrins has been synthesized in good yield for the first time. They exhibited red shifted broad absorption spectral features with high dipole moments and tunable redox properties.

Molecular characterization, computational analysis and expression profiling of Dmrt1 gene in Indian major carp, Labeo rohita (Hamilton 1822)

Sexual dimorphism of fish morphology, physiology and behavior is diverse and complex in nature. Doublesex and mab-3 related transcription factor (Dmrt) is a large protein family whose function is sexual development and differentiation in vertebrates. Here, we report a full-length cDNA sequence of Labeo rohita (rohu) Dmrt1 of 907 bp length having 798 bp of open reading frame encoding 265 amino acids. The molecular weight of rohu DMRT1 protein was found to be 28.74 KDa and isoelectric point was 7.53. DMRT1 protein contains 23 positively and 24 negatively charged amino acids with a GRAVY score of -0.618. A characteristic DM domain was found in DMRT1 protein, which is a novel DNA-binding domain. Phylogenetic analysis showed maximum similarity with Cyprinus carpio when compared with DMRT1 of other vertebrates. Molecular docking study identified active sites to be targeted for drug designing. Rohu DMRT1 was observed to interact with other proteins such as FOXL2, CYP19a1a, AMH and SOX9a. Differential expression study revealed higher expression in testis tissue implying its role in male sex differentiation and testicular development. The information generated in the present work could facilitate further research to resolve the issues related to gonadal maturation and reproduction of commercially important aquaculture species.

Unsymmetrical nonplanar 'push-pull' β-octasubstituted porphyrins: facile synthesis, structural, photophysical and electrochemical redox properties

Mixed substitution at the β-position of porphyrins influences their photophysical and electrochemical redox properties. Two new series of asymmetrically mixed β-octasubstituted porphyrins viz. MTPP(Ph)2Br5X (X = NO2 or Br and M = 2H, Co(ii), Ni(ii), Cu(ii), and Zn(ii)) have been synthesized and characterized by various spectroscopic techniques. The single crystal X-ray structure of H2TPP(NO2)(Ph)2Br5 showed a nonplanar saddle shape conformation of the macrocyclic core. Furthermore, the fully optimized geometries confirmed the saddle shape conformation of H2TPP(Ph)2Br5X (X = NO2 or Br). Electronic spectra revealed a significant bathochromic shift by appending both electron donor and acceptor substituents at the β-position of the meso-tetraphenylporphyrin skeleton, which reflects the following order H2TPP < H2TPP(NO2) < H2TPP(NO2)(Ph)2 < H2TPP(Ph)2Br6 < H2TPP(NO2)(Ph)2Br5. H2TPP(Ph)2Br5X (X = NO2 or Br) exhibited a significant bathochromic shift (Δλmax = 53-61 nm) in the Soret band and (Δλmax = 90-95 nm) in the longest wavelength Qx(0,0) band as compared to H2TPP. Nonplanar conformations and electron withdrawing β-substituents induce higher protonation and deprotonation constants for H2TPP(NO2)(Ph)2Br5 and H2TPP(Ph)2Br6 as compared to precursor porphyrins viz. H2TPP, H2TPP(NO2) and H2TPP(NO2)(Ph)2. The electronic spectral properties and redox potentials of MTPP(Ph)2Br5X (X = NO2 or Br and M = 2H, Co, Ni, Cu and Zn) are affected by β-substituents at the periphery of the porphyrin core. Redox tunability was achieved by appending push-pull substituents at the β-position of the MTPP (M = 2H, CoII, NiII, CuII, and ZnII) skeleton of the macrocycle. CuTPP(Ph)2Br6 and CuTPP(NO2)(Ph)2Br5 exhibited a dramatically reduced HOMO-LUMO gap with a difference of 0.55 V and 0.62 V, respectively as compared to CuTPP due to the push-pull effect of β-substituents and nonplanarity of the porphyrin core.