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Asymmetrically β-substituted porphyrins possessing ethyl acetoacetate or acetylacetone were synthesized. They exhibited redox tunability and higher third-order NLO coefficients due to the electron-withdrawing β-substituents and their nonplanar structure.

Two [Formula: see text]-substituted Pd(II) porphyrins, (PdTPP(NO[Formula: see text]Ph2 and PdTPP(Ph)[Formula: see text], were synthesized and characterized by various spectroscopic techniques, and their spectral and electrochemical redox properties were investigated with respect to PdTPP. The single-crystal X-ray structure of PdTPP(NO[Formula: see text]-Ph2 revealed saddle-shape conformation of the macrocyclic core of porphyrin. DFT studies revealed nonplanar saddle shape conformation of PdTPP(Ph)4 with an average deviation of [Formula: see text]-pyrrole carbon atoms from the porphyrin mean plane ([Formula: see text]C[Formula: see text] = ± 0.751 Å) and also 24 core atoms ([Formula: see text]24 = ± 0.368 Å) as compared to PdTPP(NO[Formula: see text]Ph2 ([Formula: see text]C[Formula: see text] = 0.649 Å and [Formula: see text]24 = ± 0.317 Å) due to more [Formula: see text]-pyrrole substitution. Both PdTPP(NO[Formula: see text]Ph2 and PdTPP(Ph)4 exhibited 13-19 nm and 49-59 nm red-shift in the Soret and Q[Formula: see text] bands as compared to PdTPP, respectively. PdTPP(NO[Formula: see text]Ph2 exhibited a very high dipole moment (7.32 D) as compared to PdTPP(Ph)4 (0.239 D) due to the “push-pull” effect of electron donor (phenyl) and acceptor (-NO[Formula: see text] groups at the [Formula: see text]-pyrrole positions of the macrocycle. The redox potentials of PdTPP(NO[Formula: see text]Ph2 anodically shifted ([Formula: see text]E = 0.2-0.4V) as compared to PdTPP and PdTPP(Ph)4 due to the presence of [Formula: see text]-phenyl groups and the strong electron-withdrawing effect of the nitro group. Hence the HOMO-LUMO energy gap of PdTPP(NO[Formula: see text]Ph2 decreased by 0.20 V and 0.28 V as compared to PdTPP(Ph)4 and PdTPP, respectively.

Antipodal β-diformyl porphyrin (H2TPP(CHO)2) and its metal complexes (MTPP(CHO)2, M = [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] are synthesized and characterized by various spectroscopic techniques. Diformyl porphyrins possess two electron-withdrawing formyl substituents at their β-pyrrole positions making them electron-deficient macrocycles. UV-Vis absorption spectra of MTPP(CHO)2 are red-shifted as compared to β-monoformyl/hydroxymethyl porphyrins and a further large anodic shift ([Formula: see text][Formula: see text] = 0.15 - 0.52 V) was observed in their redox potentials. Hammett plots of MTPP(X)(Y) (X = CHO, CH2OH; Y = H, CHO) showed that the HOMO-LUMO energy gap decreases with the increment in the Hammett parameter ([Formula: see text] of the substituents. DFT studies are performed for different positional isomeric diformyl porphyrins which reveal that the position of β-formyl groups affects the geometry of the porphyrin core while the symmetrical nature of 2,13-diformyl porphyrin and longer distance between two formyl groups bring quasiplanar conformation of the diformyl porphyrin macrocycle.

Two new series of unsymmetrically

We reported the efficient charge transfer studies from methylammonium lead halide, MAPbX3 (X = Br, I), perovskite nanocrystals (PNCs) to 5,10,15,20-tetraphenylporphyrin (TPP).

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.

A new series of nonplanar and unsymmetrically β-functionalized "push-pull" copper corroles, CuTPC(CHO)R

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.

A series of “push–pull” porphyrins, MTPP(MN)(TPA)2 having triphenylamine (TPA) and dicyanovinyl (MN) at antipodal positions were synthesized and characterized. They were utilized for third-order nonlinear optical measurements using kHz laser pulses.

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(YF)2, where Y is an indanedione (IND) or malononitrile (MN) group, R = H or Br and YF 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 NiII 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.

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.

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.

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.

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 (Ka ) 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.

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.

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.

Development of cost-effective, durable, and efficient bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is still required for efficient fuel cells, metal-air-batteries, and water electrolysis. For that purpose we have prepared tetrakis(3′,5′-dimethoxyphenyl)porphyrinato cobalt(II) (CoDMTPP) and 5,10,15,20-tetrakis(3′,5′-dihydroxyphenyl)porphyrinato cobalt(II) (CoDHTPP). Further, multi-walled carbon nanotubes (MWCNTs) based composites of CoDMTPP (MWCNTs-CoDMTPP) and CoDHTPP (MWCNTs-CoDHTPP) are also prepared and characterized through spectroscopy (UV–vis, FTIR, and XPS), microscopy (SEM, TEM with EDAX), X-ray diffraction, thermogravimetry, and electrochemical techniques. The materials, MWCNTs-CoDMTPP and MWCNTs-CoDHTPP are immobilized on glassy carbon (GC) electrodes, represented as GC/MWCNTs-CoDMTPP and GC/MWCNTs-CoDHTPP. They show efficient ORR activity in acidic, basic, and neutral (pH 7.0 buffer) mediums. Further, both of these electrodes exhibit significant OER activity in 0.1 M KOH, indicating the bifunctional activity in basic medium. Based on the kinetic studies, the presence of –OH in the CoDHTPP is found to enhance the ORR activity. The electrodes, GC/MWCNTs-CoDMTPP and GC/MWCNTs-CoDHTPP exhibit high methanol tolerance capacity. A very small change in onset potential of 12 mV at GC/MWCNTs-CoDMTPP and 3 mV at GC/MWCNTs-CoDHTPP electrodes are observed for the ORR after 3000 continuous potential cycles indicating the high operational stability of the modified electrodes.

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

The efficient charge transfer from methylammonium lead halide, MAPbX

Two octahalogenated nickel(II) hydroxyphenylporphyrins were synthesized and characterized as to their electrochemical and spectroscopic properties as well as their reactivity in neutral, acidic, and basic nonaqueous media. The newly synthesized complexes are represented as NiPorCl

A series of mixed β-substituted porphyrins, 2,3,12,13-tetrakis(bromo/cyano/methyl)-5,7,8,10,15,17,18,20-octaphenylporphinatonickel(II)/copper(II), MOPPX4s (X = Br, CN and CH3; M = Ni(II) and Cu(II)) were examined in 24 different solvents with varying polarity. Among the porphyrins, MOPP(CN)4 show enhanced solvent dependent optical absorption spectral features relative to other porphyrins, MOPPX4 (X = Br and CH3) and MTPPs. Although, MOPP(CN)4 (M = Ni(II) and Cu(II)) have higher electron deficiency due to electron withdrawing β-cyano groups, comparable solvent dependent absorption spectral features and opposite trend in their shift of bands relative to the corresponding MTPPBr8 were observed. The large red-shift of the absorption bands of Cu(II) and Ni(II)-mixed substituted porphyrins in polar solvents or nitrogenous bases has been suggested to the destabilization of the HOMO (b2) relative to b1 (HOMO) level due to axial ligation of the polar solvents or nitrogenous bases with the core metal ions. The greater affinity of the core metal ions towards coordinating solvents or nitrogenous bases has been attributed to the electron deficient nature of the porphyrin π-system and follow the order: MOPP(CN)4 > MOPPBr4 > MOPP(CH3)4 due to inductive/resonance effect of β-substituents rather than the nonplanarity of the porphyrin ring.

Three new 'push-pull' A3 B Zn(II)porphyrin dyes having meso-pyrenyl, carbazolyl and phenothiazine as electron donors (A) and phenylcarboxylic acid as acceptor/anchor (B) were synthesized and utilized for DSSC application. The spectral and electrochemical redox properties of these new dyes were studied and compared with trans-A2 BC Zn(II) porphyrin dyes under similar experimental conditions. Red-shifted, broadened absorption peaks, lower fluorescence quantum yields, and shortened lifetimes were observed for the A3 B dyes as compared to zinc tetraphenylporphyrin control, ZnTPP. DFT optimized structures suggested effective charge separation related to enhanced charge injection efficiency. Driving force for electron injection (ΔGinj ) and dye regeneration (ΔGreg ) calculated from the spectral and electrochemical studies predicted facile electron injection from excited dye into semiconductor TiO2 in the constructed solar cells. Phenothiazine appended dye (KP-TriPTZ-Zn) showed the highest η value of 7.3 % for PCE with greater Jsc and Voc values due to its better light harvesting ability and reduced dye aggregation as compared to other dyes. Our studies demonstrate that the dyes having multiple electron-donating groups exhibit higher photon-to-current conversion efficiency.

A new series of "push-pull"meso-substituted trans-A

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, NiII, CuII, or ZnII 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.

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.

A persubstituted porphyrin with eight entities of triphenylamines at the β-pyrrole positions of a zinc tetraphenylporphyrin

A new series of mixed β-substituted dibenzoporphyrins were synthesized, and the effect of β-substitution on the spectral and electrochemical redox properties of the macrocycle was elucidated. The synthetic route to β-tetrasubstituted dibenzoporphyrins begins with the regioselective bromination of NiTPP(Benzo)2 to afford NiTPP(Benzo)2Br4, followed by Pd catalyzed coupling reaction to access NiTPP(Benzo)2(R)4 (R = phenyl (Ph) and phenylethynyl (PE)). Synthesized benzoporphyrins exhibited red-shifted absorption spectral features with tunable redox properties. These benzoporphyrins displayed pronounced electronic effects of β-substituents on the macrocyclic skeleton. NiTPP(Benzo)2(PE)4 exhibited the lowest HOMO–LUMO gap among the series due to extended π-conjugation. Intrestingly, metal-centered oxidation of Ni(II)/Ni(III) was observed for NiOPP(Benzo)2 and NiOPP(Benzo)Br2 after an initial conversion of the neutral porphyrin to its dicationic form under electrochemical conditions.

β-substituted D-A porphyrins have been synthesized via Suzuki coupling reaction and characterized by various spectroscopic techniques. Two different electron donating moieties i.e. 4-(carbazol-9-ylmethyl)phenyl and 4-(phenothiazin-10-ylmethyl)phenyl were appended at antipodal β-positions of electron acceptor moiety i.e. H2TPP(NO2). The absorption and emission data suggested an interaction between the donor and acceptor subunits. An efficient energy transfer (78–88%) from β-substituents to macrocyclic core was supported by steady state and time resolved fluorescence measurements. Density functional theory (DFT) and time dependent-density functional theory (TD-DFT) studies support the existence of intramolecular energy and charge transfer from β-donor substituents to macrocyclic core in the dyads. Forster energy transfer studies revealed that the nature of energy transfer was mainly through bond (χTB = 0.71–0.83) in nature. The basic nature of porphyrin core was elucidated by very high protonation constants (logβ2 = 9.59–10.45). The first and second oxidation potentials of 1, 2 and their Zn(II) complexes (1a and 2a) were cathodically shifted as compared to H2TPP(NO2) and ZnTPP(NO2) due to effective electron donating nature of β-substituents which led to lower HOMO-LUMO gap.

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

We hereby report the synthesis, characterization and catalytic applications in the epoxidation of alkenes by a vanadyl porphyrin having bulky bromo substituents at the β-positions viz. vanandyltetrabromotetraphenylporphyrin (1). The synthesized porphyrin was characterized by various spectroscopic techniques like UV-visible, FT-IR, EPR, MALDI-TOF mass spectrometry and single crystal X-ray analysis. Porphyrin 1 has a nonplanar structure as indicated by its X-ray structure, DFT and electrochemical studies. 1 was analyzed for its catalytic application in the epoxidation of various alkenes. The catalytic reactions were carried out in CH3CN/H2O mixture in 3 : 1 (v/v) ratio. 1 displayed good efficiency in terms of mild reaction conditions, lower reaction temperature and minimal catalyst amount consumption. 1 exhibited excellent selectivity, high conversion efficiency and huge TOF (7600–9800 h−1) in a significantly low reaction time of 0.5 h. Catalyst 1 was regenerated at the end of various catalytic cycles making it reusable and industrially important.

meso-Tetrakis(3,5-dimethoxyphenyl)porphyrinatooxidovanadium (1) and β-octabromo-meso-tetrakis(2,6-dibromo-3,5-dimethoxyphenyl)porphyrinatooxidovanadium (2) were synthesized in excellent yields. The synthesized oxidovanadium(IV) porphyrin complexes were characterized by various spectroscopic methods such as UV-Vis, FT-IR, EPR and MALDI-TOF mass spectrometry, as well as by single crystal X-ray crystallography. The acetonitrile coordinated porphyrin 1 is relatively planar whereas 2 is highly nonplanar as shown by their crystal structures and also by electrochemical studies. Selective epoxidation studies of alkenes were successfully carried out in CH3CN/H2O as the solvent mixture at ambient temperature resulting in very high TOF numbers (12 227–14 347 h−1 for 2) even with low catalyst loadings. Remarkably, 2 biomimics the vanadium bromoperoxidase (VBrPO) enzyme with extremely high TOF values (83 333–87 719 h−1) for the oxidative bromination of thymol and some other phenols. Both the catalysts were successfully recovered at the end of the reactions, indicating their viability and industrial applicability.

We have designed and synthesized four donor-acceptor based trans-A2B2 Zn(II) porphyrin dyes with various donor moieties and phenylcarboxy as acceptor group in three steps. Two strong electron-donating groups (carbazole, phenothiazine, pyrene and bisthiophene) were attached to porphyrin core to enhance the light absorption of dye molecules and phenylcarboxy acted as acceptor group on TiO2 surface. The alkyl chains present in KP-Zn-CBZ and KP-Zn-PTZ dyes are helpful to suppress the aggregation of dyes at the semiconductor surface. The synthetic route of these dyes was facile, high yield and three steps procedure which involved MacDonald condensation followed by hydrolysis and Zn insertion. The absorption and emission bands of all four dyes were broadened and red shifted due to the charge transfer from donor groups to porphyrin moiety. A wide range of power conversion efficiency was shown by dyes and the order of ƞ was as followed KP-Zn-PTZ (5.48%) > KP-Zn-PYR (3.38%) > KP-Zn-CBZ (2.64%) > KP-Zn-BTP (1.71%). Co-sensitization of porphyrin dyes with N719 dye promoted the complementary absorption in the visible region and put a restriction on dye aggregation also which improved the cell performance. Co-sensitized KP-Zn-PTZ with N719 dye showed the highest PCE efficiency up to 8.80% with a Jsc = 17.4 mA cm−2, Voc = 0.73 V and FF = 70% which was superior to individual co-sensitized Zn(II) porphyrin dyes and N719 dye alone (ƞ = 7.3%).

[Formula: see text]-methyl fused nickel(II) porphyrin was synthesized by a facile synthetic route in excellent yield. The effect of the electron-donating methyl group on spectral and electrochemical redox properties was analyzed by comparing the electrochemistry with that of its precursors. [Formula: see text]-methylated fused nickel(II) porphyrin exhibited a red-shifted absorption spectrum ([Formula: see text] 6–13 nm) and a 180[Formula: see text]mV anodic shift in the first ring oxidation as well as a 210[Formula: see text]mV shift in reduction with respect to its Ni(II)-fused porphyrin precursor (Ni[Formula: see text]-(NH)TPP). However, the absorption spectral features and redox potentials of N-methyl fused nickel(II) porphyrin are marginally shifted as compared to its immediate precursor, [Formula: see text]-formyl Ni(II)-fused porphyrin. Notably, Ni(II)(N-CH[Formula: see text](CHO)TPP exhibited a third oxidation at 1.51[Formula: see text]mV, corresponding to oxidation of Ni(II) to Ni(III) due to the presence of “push–pull” [Formula: see text] substituents.

Several ruffled β-to-ortho-phenyl monofused metalloporphyrins (MIIMFPs) with 1,3-indanedione functionality have been synthesized by oxidative fusion of free base trans-chlorins via nickel insertion followed by the skeletal rearrangement of macrocycle. The synthesized monofused porphyrins exhibited red-shifted electronic spectral features as compared to precursor, trans-chlorins or structurally related unfused porphyrins (mono/tri-β-substituted porphyrins) due to extended π-conjugation and nonplanar conformation of the macrocyclic core. Four of the synthesized porphyrins were structurally characterized by X-ray diffraction analysis. Ring fusion resulted in twisted macrocyclic conformation, and the twist angles (the angle between 24-atom core and fused part) were found to be in the range of 20.97° to 27.97°. NiMFP(IND)Ph2 (3b) exhibited modestly ruffled conformation of the macrocyclic core which was further confirmed by higher Δ24 (0.362 A) and ΔCβ (0.279 A) values. Free base monofused porphyrins have shown...