Phenyl Porphyrin Research Articles

Design of a New Catalyst, Manganese(III) Complex, for the Oxidative Degradation of Azo Dye Molecules in Water Using Hydrogen Peroxide.

In the current work, chloro(meso-tetrakis(phenyl)porphyrin) manganese(III) [Mn(TPP)Cl] was synthesized following two steps: the preparation of meso-tetraphenylporphyrin (H⁠2TPP) and the insertion of manganese into the free porphyrin H2TPP. The compounds were characterized using SEM, FT-IR, UV, TGA/DTA, and XRD analyses. Manganese(III) meso-porphyrins exhibited hyper-type electronic spectra with a half-vacant metal orbital with symmetry, such as [dπ:dxz and dyz]. The thermal behavior of [Mn(TPP)(Cl)] changed (three-step degradation process) compared to the initial H2TPP (one-step degradation process), confirming the insertion of manganese into the core of the free porphyrin H2TPP. Furthermore, [Mn(TPP)Cl] was used to degrade calmagite (an azo dye) using H2O2 as an oxidant. The effects of dye concentration, reaction time, H2O2 dose, and temperature were investigated. The azo dye solution was completely degraded in the presence of [Mn(TPP)(Cl)]/H2O2 at pH = 6, temperature = 20 °C, C0 = 30 mg/L, and H2O2 = 40 mL/L. The computed low activation energy (Ea = 10.55 Kj/mol) demonstrated the efficiency of the proposed catalytic system for the azo dye degradation. Overall, based on the synthesis process and the excellent catalytic results, the prepared [Mn(TPP)Cl] could be used as an effective catalyst for the treatment of calmagite-contaminated effluents.

Shining light on green chemistry: BODIPY-infused porphyrin nanocomposite-enzymatic photocatalyst boosts selective aldehydes hydrogenation and organic transformation under solar spectrum

Photo-bio enzyme coupled biotransformation solar radiation driven processes grasp promising in the production of solar driven organic chemicals. Here we reported the synthesis and development of (NH2)4TPP@BODIPY photocatalyst, which was constructed from 5,10,15,20 tetrakis (4 amino phenyl) porphyrin and BODIPY {5,5-difluoro-3,7-bis((E)-4-nitrobenzylidene)-10-(4-nitrophenyl)-5,7-dihydro-3H-4l4,5l4-dipyrrolo[1,2-c:2′,1′-f][1,3,2]diazaborinine} molecule through poly-condensation mechanism resulting in the composite formation which manifest excellent light harvesting properties and photocatalytic reactions with suitable satisfactory band gap and formation of huge electrons channels which bears the organic transformation (98 %) and photo-regeneration of NADH (66.92 %) in 60 min which further enhances reduction of aldehyde resulting alcohol production. The highly selective aldehyde hydrogenation process is proposed via coordination of alcohol dehydrogenase with (NH2)4TPP@BODIPY assistant reduces from the coupling process; regeneration of nicotinamide adenine dinucleotide (NADH). Our results show an excellent benchmark for the NAD+ co-factor coupled solar-driven alcohol production via (NH2)4TPP@BODIPY photocatalyst.

Recyclable and Stable Porphyrin-Based Self-Assemblies by Electrostatic Force for Efficient Photocatalytic Organic Transformation.

Development of efficient, stable, and recyclable photocatalysts for organic synthesis is vital for transformation of traditional thermal organic chemistry into green sustainable organic chemistry. In this work, the study reports an electrostatic approach to assemble meso-tetra (4-sulfonate phenyl) porphyrin (TPPS)tetra (4-sulfonate phenyl) porphyrin (TPPS) as a donor and benzyl viologen (BV) as an acceptor into stable and recyclable photocatalyst for an efficient organic transformation reaction - aryl sulfide oxidation. By use of the electrostatic TPPS-BV photocatalysts, 0.1mmol aryl sulfide with electron-donating group can be completely transformed into aryl sulfoxide in 60min without overoxidation into sulfone, rendering near 100% yield and selectivity. The photocatalyst can be recycled up to 95% when 10mg amount is used. Mechanistic study reveals that efficient charge separation between TPPS and BV results in sufficient formation of superoxide which further reacts with the oxidized sulfide by the photocatalyst to produce the sulfoxide. This mechanistic pathway differs significantly from the previously proposed singlet oxygen-dominated process in homogeneous TPPS photocatalysis.

Synthesis of Metallo-Chromone Porphyrin Nano-Starch Sensitizers as Photodynamic Therapeutics for the Eradication of Enterococci Dental Pathogens.

Photodynamic therapy (PDT), as an advanced, alternative, and promising treatment, can inhibit dental pathogens. PDT employs the activation of photosensitizers via the light of a particular wavelength and molecular oxygen to inhibit dental pathogens. Herein, we present a comprehensive study on the synthesis and characterization of three chromone-porphyrins [Zn(II)-5-[4-chromone]-15-(4-phenyl)porphyrin (ZnCP), 5-[4-chromone]-15-(4-12 phenyl)porphyrin (DMCP), and Pd(II)-5-[4-chromone]-15-(4-phenyl)porphyrin (PdCP)]. Next, the computational study was also performed to establish the correlation between photophysical properties and theoretical calculations for those chromone-porphyrins using density functional theory and time-dependent density functional theory. Furthermore, chromone-porphyrins were encapsulated in starch nanoparticles to develop soluble nano-starch sensitizers (ZnCP-SNPs, DMCP-SNPs, and PdCP-SNPs) via the nanoprecipitation technique. Upon green light exposure, these nano-starch sensitizers exhibited excellent singlet oxygen generation ability. Moreover, final nanoformulations have been explored for pH responsiveness. Based on our intriguing findings, the chromone-porphyrin-loaded nano-starch sensitizers displayed great potential as prospective PDT to treat enterococci dental pathogens.

Excited-State Dynamics Leading Either to Triplet Formation or Coordinative Expansion following Photolysis of Cu(II)-Porphyrins: A DFT, TD-DFT, Luminescence and Femtosecond Time-Resolved Absorbance Study.

The photophysical properties of Cu(II) complexes with 5,10,15,20-meso-tetrakis(phenyl)porphyrin and 5,10,15,20-meso-tetrakis(N-methylpyridium-4-yl)porphyrin are examined via the luminescence and femtosecond time-resolved absorbance methods, respectively. These studies are supported by DFT and TD-DFT calculations, which highlight the important role played by ligand-to-metal charge-transfer states in directing the system toward either intersystem crossing to the triplet hypersurface or coordinative expansion to a five-coordinate quasi-stable intermediate. The latter processes occur when the porphyrin is photolyzed in the presence of suitably located Lewis bases. Femtosecond time-resolved absorbance measurements of Cu(II)-5,10,15,20-meso-tetrakis(N-methylpyridium-4-yl)porphyrin confirm that the coordinative expansion in water occurs in approximately 700 fs, while crossing to the triplet hypersurface takes approximately 140 fs in the same solvent. These processes are mutually exclusive, although both can occur simultaneously depending on the environment of the porphyrin. The ratio of the two processes depends on the relative orientation of the Lewis base with respect to the copper atom at the time of excitation. As a consequence, copper porphyrins such as these are excellent probes in the environment of the porphyrin and can be used to identify the location of the porphyrin when interacting with DNA fragments.

Photosensitizers combination approach to enhance photodynamic inactivation of planktonic and biofilm bacteria.

To improve bacterial photodynamic inactivation (PDI), this work analyzes the photodynamic effect caused by the combination of photosensitizers (PSs) on two bacterial models and different growth mode. Simultaneous administration of PSs from different families, zinc(II) 2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]phthalocyanine (ZnPPc4+), 5,10,15,20-tetra(4-N,N,N-trimethylammonium phenyl)porphyrin (TMAP4+), meso-tetrakis(9-ethyl-9-methyl-3-carbazoyl)chlorin (TEMCC4+) and 5,10,15,20-tetrakis[4-(3-N,N-dimethylaminopropoxy)phenyl] chlorin (TAPC) was investigated against Staphylococcus aureus and Escherichia coli, in planktonic form, biofilm and growth curve. Various PSs combinations showed greater inactivation compared to when used separately under the same conditions but at twice the concentration. However, differences were found in the effectiveness of the PSs combinations on Gram positive and negative bacteria, as well as in planktonic or biofilm form. Likewise, the combination of three PSs completely stopped E. coli growth under optimal nutritional conditions. PSs combination allows extending the range of light absorption by agents that absorb in different areas of the visible spectrum. Therefore, PDI with combined PSs increases its antimicrobial capacity using agents' concentrations and light fluences lower than those necessary to cause the same effect as single PS. These advances represent a starting point for future research on the potentiation of PDI promoted by the combined use of PSs.

Impact of Electron-Withdrawing Effect on Sigma Hole Via Bromine-Based Interactions in Zn-5,10,15,20-tetra(4-bromo-2,6-difluoro Phenyl) Porphyrin

Impact of Electron-Withdrawing Effect on Sigma Hole Via Bromine-Based Interactions in Zn-5,10,15,20-tetra(4-bromo-2,6-difluoro Phenyl) Porphyrin

Synthesis and photodynamic antimicrobial chemotherapy against multi-drug resistant Proteus mirabilis of ornithine-porphyrin conjugates in vitro and in vivo.

For the treatment of bacterial infections, photodynamic antimicrobial chemotherapy (PACT) has the advantage of circumventing multi-drug resistance. In this work, new cationic photosensitizers against multi-drug resistant Proteus mirabilis (MRPM) were designed and synthesized by the conjugation of amino phenyl porphyrin with basic amino acid L-ornithine. Their photoinactivation efficacies against MRPM in vitro were reported and include the influence of laser energy, uptake, MIC and MBC, dose-dependent photoinactivation effects, membrane integrity, and fluorescence imaging. The PACT in vivo was evaluated using a wound mouse model infected by MRPM. Photosensitizer 4d displayed high photo inactivation efficacy against MRPM at 7.81 μM under illumination, and it could accelerate wound healing via bactericidal effect. These ornithine-porphyrin conjugates are potential photosensitizers for PACT in the treatment of MRPM infection.

Molecular weight resolution of solvent resistant nanofiltration (SRNF) membranes

Engineering membranes for molecular separations in organic media is still a big challenge, especially when two closely resembling solutes have to be separated by allowing one to pass with the solvent and the other to be rejected. The so-called “resolution” of the membrane then becomes critical. Resolution reflects the difference in rejection values of the two (or more) solutes for that solvent-membrane system. Recently developed crosslinked poly(vinylidene difluoride) (XL-PVDF) and well-known crosslinked polyimide (XL-PI) membranes were prepared and tested for solvent resistant nanofiltration (SRNF). Rejections of 7 dyes (i.e. Rose Bengal (RB), Acid fuchsin (AF), Rhodamin B (RhB), Sudan Black (SB), Zinc tetraphenylporphyrin (ZTPP), and 55,10,15,20-Tetrakis(3,5-di-tert-butyl phenyl)porphyrin (TBPP) in a broad range of solvents, i.e. a set of polar solvents (water, ethanol, isopropanol), and a set of non-polar ones (butyl acetate, chloroform, xylene and toluene) were studied. As anticipated, the molecular weight cut-offs (MWCOs) of both membrane-types varied with the applied solvent type. Butyl acetate and chloroform filtrations respectively yielded the sharpest MWCO for XL-PVDF and XL-PI. The varying MWCO-curve per solvent is explained by the changing affinity of solvents and solutes for the membrane, as indicated by swelling and sorption experiments respectively.

Optical studies of carbon nano dots based composites for waste water remedy

The critical probing in order to acquire a sustainable, biocompatible and provident hybrid molecular system incorporating the renewable and abundant sources such as solar energy for environmental remediation and energy conversion is raving far and wide. The hybrid nanocomposite of synthesised Carbon Nano Dots (CNDs) and Zinc Methyloxy Tetra Phenyl Porphyrin (Zn4OMeTPP) are a supramolecular construct and high order self-assemblies which are extremely stable, easily integrable, environmental friendly, cost effective and possess appreciable tunable optoelectronic properties which are necessitated for targeting applications of streaming significance like water remediation. The constituents are synthesised via simple solution phase method and the attention has been converged on optical studies of the composite for which UV–Vis and Raman spectroscopy has been carried out. Prior to that, morphological studies have been done using XRD and FTIR. The upshot manifested by the studies is that the synthesised composite can prove to be a promising candidate for photocatalytic applications in either its sheer or hybrid form.

Synthesis and Studies of Mono-functionalized Telluradithiasapphyrins and Covalently Linked Porphyrin- Telluradithiasapphyrin Dyads.

A series of mono-functionalized aromatic 22π telluradithiasapphyrins containing functional groups such as p-bromophenyl, p-iodophenyl, p-nitrophenyl and p-trimethylsilylethynyl phenyl groups at one of the meso-positions were synthesized by condensing appropriately functionalized unsymmetrical bithiophene diol and 16-telluratripyrrane in CH2 Cl2 under acid-catalyzed conditions. To demonstrate the reactivity of mono-functionalized telluradithiasapphyrins, we synthesized the first examples of covalently linked diphenyl ethyne bridged four novel 18π porphyrin/metalloporphrin-22π telluradithiasapphyrin dyads by coupling meso-ethynyl phenyl porphyrin with telluradithiasapphyrin containing meso-iodophenyl group under Pd(0) coupling conditions followed by metalation of porphyrin unit by treating free base dyad with appropriate metal salts. The dyads were characterized and studied by mass, 1D & 2D NMR, absorption, cyclic voltammetry, fluorescence and DFT techniques. The DFT analysis showed that the porphyrin/metalloporphyrin and sapphyrin units in dyads orient with each other in different angles and Zn(II) porphyrin-sapphyrin dyad (Zn-dyad) showed minimum whereas the free base dyad showed maximum angle of deviation. NMR, absorption, and redox studies indicated that the dyads exhibit the overlapping features of their constituted monomers and maintain their individual characteristic features. The steady-state fluorescence studies revealed that the fluorescence of the porphyrin/metalloporphyrin unit was significantly quenched due to possible energy/electron transfer from the porphyrin/metalloporphyrin unit to non-emissive sapphyrin unit in dyads.

An upconverted nanoparticle-porphyrin metal-organic framework platform for near-infrared detection of nitenpyram.

A ratiometric nitenpyram (NIT) upconversion luminescence sensor UCNPs-PMOF was fabricated from a metal-porphyrin organic framework (PMOF) and pretreated UCNPs. The reaction between NIT and the PMOF releases the H2TCPP (5,10,15,20-tetracarboxyl phenyl) porphyrin ligand, which enhances the absorption of the system at 650 nm, and reduces the upconversion emission intensity of the sensor at 654 nm through a luminescence resonance energy transfer (LRET) mechanism, thus achieving the quantitative detection of NIT. The detection limit was 0.21 μM. Meanwhile, the emission peak of UCNPs-PMOF at 801 nm does not change with the concentration of NIT, and the emission intensity ratio (I654 nm/I801 nm) is used to achieve the ratiometric luminescence detection of NIT, and the detection limit is 0.22 μM. UCNPs-PMOF has good selectivity and anti-interference to NIT. In addition, it has a good recovery rate in actual sample detection, which indicates that it has high practicability and reliability in NIT detection.

Study on the triboelectric performance of porphyrin- and phthalocyanine-crosslinked enhanced fluorinated polyimide films for lateral sliding-mode triboelectric nanogenerator

• Two fluorinated polyimide films crosslinked by TAPP or TAPc were prepared. • The PI/TAPP and PI/TAPc films showed higher dielectric constant than neat PI. • The PI/TAPP and PI/TAPc exhibited smaller charge decay than neat PI in LS-TENGs. • The PI/TAPP and PI/TAPc showed higher friction coefficient stability than neat PI. In order to improve the charge retention, anti-decay ability and durability of traditional triboelectric materials in lateral sliding-mode triboelectric nanogenerators (LS-TENGs), two fluorinated polyimide films crosslinked by porphyrin tetra-amino phenyl porphyrin (TAPP) and tetra-amine phthalocyanine (TAPc) were synthesized, and their contact angles, dielectric properties, output performances and tribological properties were studied in detail. The results showed that the polyimide films crosslinked by TAPP (PI/TAPP) and TAPc (PI/TAPc) with lower surface energies had higher dielectric constants compared with neat PI and Kapton. In addition, TAPP and TAPc not only improved the electrical output with a small decay of charge density, but also reduced the wear of PI films during the whole triboelectrification process, which is attributed to the high permittivity and the crosslinked effect of PI with TAPP or TAPc. Thus, PI films with TAPP and TAPc hold great promise for dielectric research and LS-TENG applications.

Highly Antibacterial and Adhesive Hyaluronic Acid Hydrogel for Wound Repair.

Bacterial infections accompanied with wound healing often lead to more serious health hazards to patients. Therefore, it is urgent to explore a wound dressing that can promote wound repair while possessing antibacterial capability. Here, we constructed a multifunctional hydrogel dressing by a redox-initiated cross-linking reaction of methacrylated hyaluronic acid (HAMA), 5,10,15,20-tetra (4-methacrylate phenyl) porphyrin (TPP), and dopamine methacrylamide (DMA), named HAMA-TPP-DMA, with broad-spectrum photodynamic antibacterial capability, where the aggregation of TPP photosensitizer units could be greatly inhibited to produce more singlet oxygen. The hydrogel has excellent biodegradability and biocompatibility, providing favorable conditions for wound healing. Furthermore, the incorporation of dopamine into the hydrogel gives the wound dressing with enhanced adhesiveness, benefiting for the wound repair. More importantly, the antibacterial experiments in vitro and mice wound models in vivo showed that the HAMA-TPP-DMA hydrogel can significantly resist bacteria and accelerate the wound healing in mice (the closure rate > 98% after 15 days). Thus, this hydrogel dressing with superior antibacterial infection and wound healing capability provides a promising strategy in wound repair.

Unveiling the influence of 5,10,15,20-tetrakis (4-carboxyl phenyl) porphyrin on the photogenerated charge behavior and photoelectrochemical water oxidation of hematite photoanode

Coupling porphyrins with semiconductors is demonstrated as one of effective means to facilitate the separation of photogenerated charge in dye-sensitized solar cells as well as photocatalytic hydrogen production. However, there are limited reports about exploring the effect of porphyrin on the behavior of photogenerated charges and photoelectrochemical (PEC) water oxidation performance. Herein, we have built a hybrid photoanode containing Ti doped α-Fe2O3 (Ti-Fe2O3), 5,10,15,20-tetrakis (4-carboxyl phenyl) porphyrin (H2TCPP) and cobalt phosphate (CoPi) cocatalyst. Because of the appropriate band alignment of Ti-Fe2O3, H2TCPP and CoPi, the photogenerated holes are transferred directionally from Ti-Fe2O3 to CoPi across H2TCPP, which boosts the separation efficiency of CoPi/H2TCPP/Ti-Fe2O3 in turn. Meanwhile, CoPi/H2TCPP/Ti-Fe2O3 possesses higher injection efficiency as well. Under the double guarantee of high separation efficiency and injection efficiency, CoPi/H2TCPP/Ti-Fe2O3 yields an impressive photocurrent density of 1.84 mA/cm2 at 1.23 V vs. reversible hydrogen electrode (RHE), which is much higher than that of CoPi/Ti-Fe2O3. This structure design describes an appealing maneuver to facilitate the directed migration of photogenerated charges and then enhance the PEC water oxidation performance.

Zinc, Tin and Silver Porphyrins (TPP, TCPP, TMPP, THPP, TPPS, TMPyP) as photosensitizers in antibacterial photodynamic therapy for chronic wounds: A screening study

Continuous proliferation of bacteria in a wound delays its healing process, and could further extend to becoming a chronic wound infection. The effectiveness of different porphyrins as a photosensitizer in antibacterial photodynamic therapy for the inactivation of some wound-colonizing bacteria was studied as a screening experiment. Meso-tetra(4-methoxyphenyl) porphyrin, (TMPP), meso-tetra(4-hydroxyphenyl) porphyrin (THPP), meso-tetra(4-carboxyphenyl) porphyrin, (TCPP), meso-tetra(N-methyl-4-pyridyl) porphyrin, (TMPyP) were synthesized, each complexed with zinc, tin and silver. The in-vitro and photo-toxicity properties of the porphyrins and their complexes were assessed on some selected wound colonizing multi-drug resistant bacterial strains (Staphylococcus aureus, Klebsiella pneumoniae, Proteus mirabilis, and Escherichia coli) using agar well diffusion method. Photo-toxicity of the compounds were investigated using a 100-Watt tungsten lamp while the in-vitro toxicity was carried out in the dark. The results were compared with previously reported work carried out by this group on meso-tetra(phenyl)porphyrin (TPP), meso-tetra(4-sulphonatophenyl) porphyrin, (TPPS) and their corresponding Zn, Sn and Ag complexes. Most of the porphyrins showed biocidal activities against three of the test isolates with an exception to Proteus sp. ZnTMPyP and ZnTHPP only showed photo-toxic activities against the four test isolates. While SnTHPP, ZnTPPS, ZnTCPP, and SnTCPP all exhibited both toxic and photo-toxic activities against all four bacterial isolates. The Ag-porphyrins had the poorest inactivation activity.

Synthesis of fluorescent molecular switches based on porphyrinoids covalently linked with redox active ligands

5,15-bis(1-hydoxy-2,6-di-tert-butyl-phenyl)10,20-bis-(pentaphenyl-phenyl)phenyl porphyrin and its Nickel complex were synthesized. Oxidation with NOBF4 gave 5,15bis(1-oxo-2,6-ditertairy-butyl-phenyl)10,20-bis(pentaphenyl-phenyl)phenyl-porphodimethene and Ni bis(1-oxo-2,6-ditertairy-butyl-phenyl)10,20-bis-(pentaphenylphenyl)phenyl porphodimethene. The porphyrin conjugates were characterized by NMR, mass, and UV–visible spectroscopy for structural elucidation. The density functional theory studies revealed a decrease in the highest occupied and the lowest unoccupied molecular orbital (HOMO-LUMO) energy gaps in the oxo-porphodimethenes. The photochromism and fluorescence characteristics were also studied. The porphyrin moieties were found to be desirable for the reversible light-driven fluorescent molecular switches.

CoO Nanotubes Loaded on Graphene and Modified with Porphyrin Moieties for Colorimetric Sensing of Dopamine

In this paper, CoO nanotubes loaded on the surface of graphene oxide (GO) have been first modified by 5,10,15,20-tetrakis(4-carboxyl phenyl)porphyrin (Por) by a hydrothermal method. Por/CoO/GO exhibits excellent peroxidase-like activity, which is evaluated by virtue of the chromogenic substrate 3,3,5,5-tetramethylbenzidine (TMB). In the presence of H2O2, Por/CoO/GO nanoperoxidase can rapidly catalyze colorless TMB to be oxidized into blue oxTMB, which is distinguished visually in 1 min. The experimental data including fluorescence and electrochemistry data and radical scavengers confirm that the catalytic mechanism of Por/CoO/GO is ascribed to electron transfer between substrates, as well as produced active species (h+ and •O2–). Based on Por/CoO/GO nanoperoxidase, a fast colorimetric sensor for H2O2 has been established for a wide range of concentrations (0.1–3 mM) with a lower limit of detection (LOD = 0.2942 mM). Notably, the blue color of oxTMB can be gradually faded in the presence of dopamine (DA) with various concentrations. Thus, a fast, cheap, and convenient colorimetric sensor has been designed to monitor DA in a wide range (0.2–10 μM) with a much lower LOD (0.1391 μM). The Por/CoO/GO-based colorimetric platform has been validated by determining DA in real serum samples.

Fluorescence Spectroscopy of Porphyrins and Phthalocyanines: Some Insights into Supramolecular Self-Assembly, Microencapsulation, and Imaging Microscopy.

The molecular interactions of anionic tetrasulfonate phenyl porphyrin (TPPS) with poly(amido amine) (PAMAM) dendrimers of generation 2.0 and 4.0 (G2 and G4, respectively) forming H- or J-aggregates, as well as with human and bovine serum albumin proteins (HSA and BSA), were reviewed in the context of self-assembly molecular complementarity. The spectroscopic studies were extended to the association of aluminum phthtalocyanine (AlPCS4) detected with a PAMAM G4 dendrimer with fluorescence studies in both steady state and dynamic state, as well as due to the fluorescence quenching associated to electron-transfer with a distribution of lifetimes. The functionalization of TPPS with peripheral substituents enables the assignment of spontaneous pH-induced aggregates with different and well-defined morphologies. Other work reported in the literature, in particular with soft self-assembly materials, fall in the same area with particular interest for the environment. The microencapsulation of TPPS studies into polyelectrolyte capsules was developed quite recently and aroused much interest, which is well supported and complemented by the extensive data reported on the Imaging Microscopy section of the Luminescence of Porphyrins and Phthalocyanines included in the present review.

Core modified freebase porphyrins in glass matrix for nonlinear optical properties

Two different types of freebase porphyrins with variation in the central core, namely H2TPP (meso-5,10,15,20- tetrakis phenyl porphyrin) and HSTPP (meso-tetrakis 5,10,15,20-tetra-phenyl-23-H-21-thiaporphyrin) were introduced into the borate glass matrix and developed the thin films by melt quenching technique. Due to core modification and extended non-planarity in the glass matrix, the absorption spectrum of HSTPP shows a strong redshift in the soret and Q bands. Emission spectra of HSTPP show an intense emission at 739 nm (S1 → S0) and ~ 505 nm due to coordination of boron atom at the central core and freezing of N-BO3 vibrations furnishes slow relaxation from higher energy states. Comparison studies are made by treating with BF3O(C2H5)2 to mimic structure in the borate glass matrix due to boron coordination at the central core. The excited state lifetimes are shortened due to BF3 interaction in the solution as well as in the borate glass matrix endowing its potential to develop the optical limiting devices. Nonlinear optical studies reveal reverse saturable absorption (RSA) behaviour in the picosecond (ps) region and show enhanced two photon absorption (TPA) by core modification. Optical power limiting measurements on HSTPP in glass matrix delivers a better limiting threshold value of 15.2 mJ/cm2.