Value Of Molar Extinction Coefficient Research Articles

Enhancing instrumental sustainability: a spectrophotometric approach for quantifying iodate in nutritionally significant salts through the adaptation of the classical iodometry method

With the primary objective of transitioning from the classical iodometric method to an instrumental approach, preserving precision in the analytical process, this study presents the development of a spectrophotometric method for quantifying iodate (iodine equivalent) in nutritionally significant salts. Therefore, the wavelengths of maximum absorption of the I3- (350.8 nm) and I3-starch (574.1 nm) complexes were determined. The complexes demonstrated stability, as indicated by the respective molar extinction coefficient values (ε) obtained over the course of the reaction time (measured up to 1h, at 5-minute intervals, and at 28°C), for concentrations ranging from 7.81×10-6 to 1.25×10-4 mols/L of KIO3. A linear correlation between concentration and absorbance was established within the specified concentration range, with detection and quantification limits defined as 0.09 and 0.29 mg/L (350.8 nm) and 0.13 and 0.39 mg/L (574.1 nm), respectively, and calculated recovery of 102.9%. The reproducibility of the method was assessed by varying the analyst, the equipment, and the analysis day. Using the developed method, it became feasible to quantify the elemental iodine equivalent in three commercially available salts commonly employed for food purposes. When compared to the classical/traditional iodometric method, the spectrophotometric method for quantifying iodate in salts showcases sustainability with minimized solvent and reagent usage, reduced waste generation, shorter analysis time, and lower sample requirements, aligning with environmentally conscious analytical practices.

Enhanced Optical and Thermal Properties of a Novel Yellow Quinophthalone Derivative for Color Filter Colorants in Image Sensors

Herein, the design and synthesis of novel yellow quinophthalone derivatives, 4,5,6,7‐tetrachloro‐2‐(6‐chloro‐2‐(3‐hydroxy‐1‐oxo‐1H‐cyclopenta[b]naphthalen‐2‐yl)quinolin‐4‐yl)isoindoline‐1,3‐dione (pC‐QP) and 4,5,6,7‐tetrachloro‐2‐(7‐chloro‐2‐(3‐hydroxy‐1‐oxo‐1H‐cyclopenta[b]naphthalen‐2‐yl)quinolin‐4‐yl)isoindoline‐1,3‐dione (mC‐QP), are used for use as yellow colorants in image sensors. The synthesized compounds are designed to modulate the optical properties based on the substituted positions of the chloride group within the quinophthalone structure. The solubility of pC‐QP and mC‐QP in propylene glycol monomethyl ether acetate solvent is found to be 0.08 and 0.15 wt%, respectively. The molar extinction coefficient values of pC‐QP and mC‐QP in solution are determined to be 3.14 × 104 and 3.62 × 105 L mol−1 cm−1, respectively. The transmittance of mC‐QP meets commercial requirements, exhibiting less than 0.3% between 412 and 475 nm and over 91% above 530 nm. Both pC‐QP and mC‐QP demonstrate high thermal stability with decomposition temperatures of 464 and 393 °C, respectively. As a result, mC‐QP emerges as an excellent candidate material for use as a yellow colorant in image sensors due to its outstanding properties.

A novel application of synthesised based squarylium dyes on nylon 6, and silk woven fabrics

Abstract Squarylium dyes were synthesized and characterized by different spectrometric techniques using FT-IR, UV-visible and GC–MS, the dyes gave molar extinction coefficient values greater than 5.2812 × 105 L mol−1 cm−1. Their fastness properties in respect to wash, light, perspiration and hot pressing on nylon 6, and silk fabrics were analyzed, effects of time, temperature, carrier concentration and pH was also investigated and reported. The dyed fabrics showed good to very good wash, light fastness, and perspiration good to very good hot pressing on nylon 6 and good to very good on silk fabric, respectively. The dye-bath exhaustion was found to be between 76 and 92% on nylon 6 and 57 and 85% on silk, respectively. The percentage exhaustion on nylon 6 was found to be very good to excellent but on silk it was found to be good to very good. These studies showed that squarylium dyes can be applied to nylon 6 and silk fabrics, but better performance was found on nylon 6 than silk fabric.

Environment-friendly and high-performance azo dye substitutes for enhanced optical characteristics and color fastness: Design and screening, risk assessment and mechanism analysis

Azo Dyes (ADs) are one of the most widely used dyes as they are characterized by high molar extinction coefficient and color fastness. However, it is difficult to remove them from the environment because of their stable structure. One of the bottlenecks in this field is to design environment-friendly and high-performance AD substitutes. Disperse Blue 79, which is commonly used in the dye industry, has been used as a target molecule for designing AD substitutes. A total of 27 substitutes with higher comprehensive effect value of molar extinction coefficient and color fastness (amplification > 20 %) were designed. After the assessment of environmental characteristics, stability and human health risk using the 3D-QSAR, molecular docking, density functional theory (DFT), and toxicokinetic techniques, the Derivative-47 was screened out. The synthetic possibility and characteristic enhancement mechanism of Derivative-47 were calculated using DFT and time-dependent density functional theory (TDDFT). Results showed the designed substitutes could be potentially synthesized in real environment (Gibbs free energy = −122.37 a.u < 0). The change in MO pairs, orbital transition and the electron transfer characteristics between the ground and excited states were the main reasons for the enhancement of molar extinction coefficient. Moreover, the increased color fastness could be primarily related to the reaction intensity of nucleophilic reaction site and the ability of molecules to lose electrons. This study aims to establish a system that integrates design, selection, and evaluation processes, provides new insights for the design of environment-friendly AD substitutes with higher molar extinction coefficient and color fastness.

NIR emitting BODIPY dyes for pH sensing

The ease of functionalization of BODIPY dyes provides scope for preparing pH indicators by introducing suitable functional groups. In this work, two dimethylamino substituted BODIPY dyes 3 and 4 with styryl and phenylbuta-1,3-dienyl groups introduced at the 3,5-positions were synthesized, characterized, and studied for use as pH indicators. Incorporation of the electron-rich vinylene substituents yielded dyes that absorb in the NIR region with emission wavelengths of 796 and 797 nm for 3 and 4, respectively, in dimethylsulfoxide (DMSO). Time-dependent density functional theory (TD-DFT) calculations were performed to study the effect of adding an extra alkene bond in 4 on the photophysical properties. The extra alkene bond in 4 resulted in a 3 nm shift in the main NIR region absorption band, lower molar extinction coefficient values, higher emission wavelength, and a decrease in fluorescence quantum yield in all solvents studied. Upon protonation of the amino groups, a large blue shift is observed in both the absorption and emission wavelengths, along with an increase in the fluorescence quantum yields and longer fluorescence lifetimes. The [Formula: see text] values for 3 and 4 were estimated to be 2.9 (± 0.05) and 1.2 (± 0.05), respectively.

Applications of spectroscopic techniques to the study of monomer–dimer equilibria for methylene blue in aqueous solutions containing ionic liquid: Probing the structural interactions involving water and ionic liquids

An understanding of the nature of interaction and bonding in dye aggregation process is important for such diverse problems and applications such as stacking interactions in biomolecules, staining properties, photodynamic therapy for cancer, energy transfer in lasing technology and energy transfer and electron transfer processes. In present communication we report visible absorption spectrums and their analysis for the dye methylene blue (MB) in concentration range of 1∙10–6 – 1∙10–4 M in aqueous solutions containing ionic liquids namely, 1–ethyl–3–methyl–imidazolium bromide, 1–butyl–3–methyl–imidazolium bromide and 1–hexyl–3–methyl–imidazolium bromide at 298 ± 1. In this concentration range of MB only Monomer ⇌ Dimer equilibria for the dye exist and hence the spectral characteristics in the visible range of 550–700 nm have been examined. The spectrums obtained are compared with those obtained in aqueous solutions of NaCl. Using suitable developed method of estimating molar absorption extinction coefficient values, the equilibrium constant values are obtained at various ionic strengths of imidazolium ions. It has been found that monomer and dimer absorption maximum occur at 665 and ≈605/610 nm, respectively, do not get much altered on addition of imidazolium ions. The extent of interaction between the MB and imidazolium cations varies with the concentration of imidazolium cations as well as the nature of imidazolium cations, that is, the chain length of the substituents. The dimer dissociation constant values extrapolated to zero ionic strength of ionic liquids exhibit systematic alteration with respect to alteration of chain length in imidazolium cations. The different interactional phenomena such as the formation of ion–pairs, ion–pair complexes, dimer dissociation, solubilization of monomers and binding of MB with imidazolium cations have been examined. The transfer standard free energy changes have been calculated for the transfer of dimers from aqueous solutions to aqueous solutions containing ionic liquids. The changes in dimer geometry from sandwich type and end–on–end types also have been studied. It is observed that the contribution to the interaction energy is mainly from van der Waals type and dispersion forces, in addition to short range forces involving multipoles. The binding of monomers with imidazolium cations is also examined in terms of formation of micellar type aggregates in solution phase. It is proposed that the water structural interaction and hydrophobic interactions are the major factors in the formation and dissociation of aggregates.

Quantitative and qualitative spectroscopic parameters determination of major cannabinoids

Cannabis based products are widely used for various medicinal conditions. Currently, the most common method to identify and quantify cannabinoids are liquid chromatographic methods coupled to UV-VIS or mass spectrometric detectors. As cannabinoids are fluorescent compounds, fluorescent-based detection methods are gaining increasing interest. Consequently, a comprehensive qualitative and quantitative determination of fluorescence characteristics of major cannabinoids is warranted. In the present study we have determined the fluorescent excitation-emission-spectrum of 13 major cannabinoid standards and calculated their molar extinction coefficient (ε) and quantum yield (Φ) values. Furthermore, we examined the correlation between ε and Φ to available physico-chemical substance descriptors, namely, octanol/water partitioning coefficient, molar weight and boiling point. The cannabinoids displayed a characteristic fluorescence excitation (225–400 nm)-emission (300–525 nm) signal. Neutral and acid cannabinoids could be distinguished based on their characteristic excitation-emission spectrum, namely neutral cannabinoids exhibited maximal intensities at 280 nm excitation and 300 nm emission, while acidic cannabinoids displayed maximal intensity at 300 nm excitation and 400 nm emission. Moreover, cannabinoids with overlapping UV spectrum (such as Δ9-trans-tetrahydrocannabinolic acid, cannabidiolic acid and Cannabigerolic acid) were found to have overlapping fluorescence excitation-emission spectrum, due to the same number of conjugated double bonds and the presence or absence of a carboxylic group. The calculated ε and Φ values were found to negatively correlate with each other. The spectral data provided hereby could assist to develop tools for initial screening of extracted samples for the presence of cannabinoids.

Effect of Solvent on the absorbance maxima (λmax) of Standard Plot of Thiocolchicoside

Standard plot of Thiocolchicoside was constructed in distilled water, 0.01M PBS, n-octanol, ethanol, methanol, 0.9% w/v NaCl and mixture of acetonitrile: water (70:30). Peak of stock solution was observed at a particular wavelength (λmax) and various dilutions of that stock solution were prepared and absorbance value of every dilution was observed at that particular wavelength and corresponding to this regression coefficient (r2), slope value (m) of plot and molar extinction coefficient of drug was observed. As stock solution of Thiocolchicoside was prepared in various solvents with different concentration of stock solution at particular λmax value. All the stock solutions of Thiocolchicoside were scanned in UV region i.e. from 200 nm-400 nm.

Azulene-Containing Squaraines for Photoacoustic Imaging and Photothermal Therapy.

Photoacoustic imaging (PAI) guided photothermal therapy (PTT) can realize real-time diagnosis and in situ treatment of cancer at the same time. Absorption in the near-infrared (NIR) region with large molar extinction coefficient (ε) and high value of photothermal conversion efficiency (PCE) are key prerequisites for photothermal agents (PTAs) to realize dual PAI and PTT treatments. Squaraines have stable quinoid structures with strong planarity and rigidity, in favor of the NIR absorption and high ε values. On the other hand, azulene derivatives mostly have very faint fluorescence emission, which is beneficial for photothermal transformation. Herein, two azulene-containing squaraines Az-SQ-1 and Az-SQ-2 are synthesized as high-performance PTAs. In comparison with Az-SQ-1, Az-SQ-2 possesses larger εmax of 3 × 105 M-1 cm-1 at 780 nm in organic solution and higher PCE of 53.2% in the form of nanoparticles under 808 nm laser irradiation. Accordingly, Az-SQ-2 NPs present stronger photoacoustic signals (about 15.1-times the background signal) and more efficient suppression of tumor growth. Our research indicates that the introduction of azulene unit to traditional NIR dyes is a simple but effective approach to obtain outstanding PTAs in the aspect of phototheranostics.

Preclusion of methemoglobinemia caused by nitrate drugs in diabetics and nondiabetics: Possible role of Vitamin C

The drugs containing nitrates like isosorbide dinitrate, isosorbide mononitrate and glyceryl trinitrate, etc., trigger the oxidation of hemoglobin which is manifested in the pathological disorder named methemoglobinemia. It was considered interesting to investigate the preventive roles of vitamin C towards the toxic effects of nitrate containing drugs used for the treatment of angina. The aim is to find whether these drugs need to be administered with special care to diabetic patients who are more prone to develop methemoglobinemia. Vitamin C (500 mg/day) was administered orally to reduce the methemoglobin (metHb) level in both the diabetic and nondiabetic patients consuming nitrate containing drugs regularly, keeping diabetic and nondiabetic patients not on nitrate drugs as control. Concentration of metHb and hemoglobin A (HbA) was estimated spectrophotometrically assuming the molar extinction coefficient values of metHb as 3.78 mM‐−1 cm‐−1 at 630 nm and HbA as 125,000 M ‐−1 cm ‐−1 at 415 nm. MetHb level was found to be lower after the treatment with vitamin C for 30 consecutive days than that before the trial with statistically significant two tailed p value. Additionally, fasting insulin level was also found to decrease after 4 weeks of consumption of vitamin C with moderate lowering of fasting serum glucose level as well, indicating a higher insulin sensitivity for the treated patients.

Influence of UV irradiation on the structural and optical properties of Ch-HPQ thin films

The influence of ultraviolet (UV) irradiation on the structural, linear optical and non-linear optical properties of 2-Amino-4-(2-chlorophenyl)-6-ethyl-5-oxo-5,6-dihydro-4H-pyrano [3,2-c] quinoline-3-carbonitrile (Ch-HPQ) thin films is elaborated. The morphology of the UV irradiated, for different irradiation times, Ch-HPQ thin films is studied using both scanning electron microscopy and X-ray diffraction and compared with the UV non irradiated one. The transmittance and reflectance spectra of Ch-HPQ thin films are studied based on spectrophotometric measurements in the spectral range (200–2500) nm. Several parameters (e.g. the molar extinction coefficient, the onset and optical energy gap values) are calculated from the absorption spectra. Dispersion of the studied material is explained by Wemple and Di Domenico single-oscillator model. The influence of UV irradiation on the loss functions is discussed. The theoretical calculations of the non-linear optical parameters such as third order non-linear susceptibility and the non-linear refractive index are investigated from linear optical parameters using semi-empirical relations. The homogeneity of Ch-HPQ thin films are found to be stable under the UV irradiation which recommends using this material in optoelectronic applications.

Effect of solvent on the photophysical properties of isoxazole derivative of curcumin: A combined spectroscopic and theoretical study

The present work aims to decipher the photophysics of a β-diketo modified curcumin analog named isoxazole derivative of curcumin (IOC). IOC itself happens to be a potential drug molecule possessing numerous biological applications such as; anti-cancer, anti-malarial, anti-Alzheimer’s, anti-Parkinson’s etc. Herein, the photophysical properties of IOC have been explored in various sets of solvents. In order to investigate, steady state and time resolved spectroscopy have been utilized as a tool. To elucidate the experimental observations at molecular level, electronic structure calculations with density functional theory (DFT) as well as classical molecular dynamics (MD) simulations in explicit solvents have been deployed. The DFT has established that the most stable ground state electronic structure of the IOC molecule is the all trans- planar conformation where the conjugated pi-electrons are delocalized over the entire molecule. The MD simulations have provided an insight into the specific and non-specific interactions with the solvent molecules. Steady state spectroscopic techniques have shown that both the absorption and emission maxima experienced a traditional red shift upon increase in the solvent polarity. The absorption maxima for IOC got red shifted from 332 nm in hexane to 344 nm in DMSO. However, the red shift in the emission maxima is more pronounced than that of absorption maxima starting from 356 nm in hexane to 431 nm in water. The value of molar extinction coefficient has also been determined for IOC in different solvents from the concentration dependent absorption spectra. The time correlated single photon counting (TCSPC) data has revealed that the excited state of IOC molecule could relax via three probable pathways. Also, the overall process of decay of the excited state is comparatively slower in case of non-polar solvents. On the other hand, the fluorescence lifetime has been observed to be unusually low in case of dimethyl sulfoxide (DMSO) as compared to its other fellow polar aprotic solvents.

DNA Binding, DFT and Spectroscopic Studies of a Charge Transfer Complex Consisting of a Bioactive Donor 1-(2-Methylbenzyl)piperazine

A bioactive donor, 1-(2-methylbenzyl)piperazine is used to synthesize a new charge transfer complex (CTC) with the π-acceptor p-chloranil (p-CHL), which is characterized spectrophotometrically. The quantitative estimation of electronic interaction of the acceptor with the donor has been examined in acetonitrile (AN). The 1:1 composition of the CTC is confirmed by Jobs’ method of continuous variation and spectrophotometric (at $$\lambda$$ max 554 nm) methods at 298 K. The Benesi–Hildebrand method gives the formation constant (KCT) and molar extinction coefficient (e) values of CTC. The spectral analysis was used to characterize CTC and its stability in solution and in the crystalline form. A DNA binding study of the CT-complex was carried out using UV–visible spectroscopy. A density functional theory (DFT) study of the CTC (gas phase/PCM) at using the B3LYP functional and 6-31G(d,p) basis set supports the experimental work. The optimization of the frontier molecular orbital surfaces was carried out by using the DFT-gasphase/PCM correlation methods. Mulliken atomic charges and reactive parameters of acceptor and donor recommend the MBPZ acts as a good electron donor and p-CHL acts as a good electron acceptor to form a highly stable electron transfer complex.

Triphenylamine-based phenylhydrazone-indolium cationic dyes for solid-state DSSC applications

D-π-A architecture metal-free organic dyes, with a triphenylamine phenylhydrazone unit as electron donor and 5-carboxy-1-butyl-2,3,3-trimethyl-3H-indolium iodide as an electron withdrawing group, were designed and synthesized for solid-state dye-sensitized solar cells. These dyes demonstrate strong absorption between 500 and 800 nm, high molar extinction coefficient values (ε > 104) and have proper electronic energy levels as promising sensitizers.

Calculating Resin Functionalization in Solid-Phase Peptide Synthesis Using a Standardized Method based on Fmoc Determination.

Solid-phase synthesis is the method of choice for peptide preparation in both research and industrial settings. The whole synthetic process is governed by the initial functionalization of the resin. Although the literature provides several methods to determine such functionalization, the addition of an Fmoc-amino acid and the posterior spectrophotometric measurement of the dibenzofulvene adduct formed after Fmoc removal is the most widely used for this purpose. However, a range of molar extinction coefficient (ε) values and even wavelengths are currently used in the field, with no standardization of the method. Here, we propose a single-point standardization method that involves a standard solution of the corresponding amino acid to be checked that is prepared freshly at the time of the analysis.

Synthesis and characterization of some novel Mn(III) glycinato complexes with catalytic applications

Tris(glycinato)Mn(III) and its mixed ligand complexes with azido-, thiocyanato-, chloro- and bromo- groups have been synthesized and characterized by UV–Vis spectrophotometry, IR spectrophotometry, elemental analysis, magnetic susceptibility measurements, thermal analysis, Dart-mass spectrometry, EPR spectral studies, and X-ray powder diffraction studies. The molar extinction coefficient values of the complexes are in the range of spin allowed 5T2g → 5Eg transitions. The magnetic susceptibility measurements of all the complexes confirmed the presence of four unpaired electrons and high spin d4 systems. Room temperature EPR spectrum gives g isotropic value 2.002 indicative of octahedral geometry for the complex. PXRD studies suggest monoclinic system with space group P21/c with a = 9.1382(60) Å, b = 15.5340(11) Å, c = 10.2576(68) Å, and β = 110.598(15)°. The particle size of the complexes lies in the range 26.60–38.79 nm. The tris(glycinato)Mn(III) is an efficient heterogeneous catalyst for decolorization of Xylenol Orange and Methyl Red in the presence of H2O2. It also initiates polymerization of acrylonitrile.

Direct UV photolysis of pharmaceutical compounds: Determination of pH-dependent quantum yield and full-scale performance

When using municipal wastewater as a potable water source, advanced treatment is mandatory for the removal of trace organic contaminants, including pharmaceuticals. UV-radiation (254 nm) is frequently used in combination with hydrogen peroxide at the end of the advanced treatment train for simultaneous disinfection and degradation of trace organic contaminants. In this work, a comprehensive study on the direct UV photolysis of eleven organic compounds (including ten pharmaceuticals and N-Nitrosodimethylamine (NDMA)) was conducted at varying pH of 5–8 using a collimated beam apparatus. Molar extinction coefficient (ε) and quantum yield (QY) values of different ionic forms (cationic, neutral and anionic) for eleven organic compounds were estimated in the tested pH range. Furthermore, direct UV photolysis at a full-scale UV photoreactor with 30 low-pressure UV lamps was performed at pH 6.2 and 7.8 by varying water flow rates (375–2700 L min−1) and UV fluences (400–4000 mJ cm−2). A process model was developed to determine the log reduction of the test compounds. The model combines a Lagrangian fluence model in the photoreactor with a pH-dependent photochemical kinetic model that ulilized the measured molar extinction coefficient and quantum yield values. The observed log reductions matched well with the model predictions for most of the tested compounds.

New 2-methoxy-4,6-bis(4-(4-nitrostyryl)phenyl)nicotinonitrile: Synthesis, characterization and DSSC study

A new 2-methoxy-4,6-bis(4-(4-nitrostyryl)phenyl)nicotinonitrile (W-NO2) has been synthesized and the photovoltaic performances in dye‐sensitized solar cells (DSSCs) are investigated by utilizing it as co-sensitizer dye. From the study, its molar extinction coefficient value is found to be much higher than the N719 and the co-sensitized DSSC device showed a 1.78 times better efficiency than the N719 based devices. Preliminary DSSC results also revealed that the molecular architecture of dye (W-NO2) can be effectively utilized as a co-sensitizer along with the N719 to increase the spectral coverage as well as to achieve improved efficiency.

Transparent Luminescent Solar Concentrators Using Ln3+-Based Ionosilicas Towards Photovoltaic Windows

The integration of photovoltaic (PV) elements in urban environments is gaining visibility due to the current interest in developing energetically self-sustainable buildings. Luminescent solar concentrators (LSCs) may be seen as a solution to convert urban elements, such as façades and windows, into energy-generation units for zero-energy buildings. Moreover, LSCs are able to reduce the mismatch between the AM1.5G spectrum and the PV cells absorption. In this work, we report optically active coatings for LSCs based on lanthanide ions (Ln3+ = Eu3+, Tb3+)-doped surface functionalized ionosilicas (ISs) embedded in poly(methyl methacrylate) (PMMA). These new visible-emitting films exhibit large Stokes-shift, enabling the production of transparent coatings with negligible self-absorption and large molar extinction coefficient and brightness values (~2 × 105 and ~104 M−1∙cm−1, respectively) analogous to that of orange/red-emitting organic dyes. LSCs showed great potential for efficient and environmentally resistant devices, with optical conversion efficiency values of ~0.27% and ~0.34%, respectively.

Synthesis and in vitro photobiological studies of porphyrin capped gold nanoparticles $$^{\S }$$ §

We describe the synthesis and characterization of a thiol-functionalized porphyrin derivative 2 and its gold nanoparticle conjugates. The porphyrin 2 exhibited its characteristic intense Soret absorption at 420 nm with a molar extinction coefficient value of $$3.6\times 10^{5}\, \hbox {M}^{-1}\, \hbox {cm}^{-1}$$ and good fluorescence in the region of 650–660 nm. The porphyrin-capped gold nanoparticles (POPNPs) were synthesized from the citrate-capped gold nanoparticles by the ligand exchange method and characterized by spectroscopic and morphological analyses (UV–Vis, DLS and TEM). The broadening of the absorption spectrum and quenching of the fluorescence intensity for the porphyrin gold nanoconjugates suggest efficient incorporation of the porphyrin moiety onto the gold surface. The results of DLS and TEM analyses indicate that the nanoconjugate POPNPs are uniformly spherical in shape with a size of ca. $$25 \pm 5\, \hbox {nm}$$ and exhibits a negative zeta potential value of $$-\,16.0 \pm 2\, \hbox {mV}$$ . The singlet oxygen generation efficiency of the porphyrin 2 and POPNPs was calculated and are found to be ca. $$0.53 \pm 0.02$$ and $$0.43 \pm 0.03$$ , respectively. The in vitro photobiological studies revealed that POPNPs exhibited enhanced photodynamic activity compared to their parent porphyrin derivative 2 with an $$\hbox {IC}_{50}$$ value of $$5\, \upmu \hbox {M}$$ in MDA MB 231 cell lines. The mechanism of the cell destruction was studied by Annexin-FITC and confirmed through TMRM assay. We observed the increase in the percentage of cell population corresponding to the late apoptotic stage ca. 37.7% and 51.2% for 5 and $$10\, \upmu \hbox {M}$$ of POPNPs, respectively, thereby demonstrating their apoptotic-mediated cell destruction and use in PDT applications. Synopsis We synthesized a thiol-functionalized porphyrin-based sensitizer 2 and its gold nanoparticles (POPNPs) and have investigated their photophysical properties, singlet oxygen generation and in vitro photobiological efficacy. Our results demonstrate that the incorporation of the sensitizer onto the surface of nanoparticles not only improved its solubility in the aqueous medium, photophysical and photobiological properties but also its potential as a novel sensitizer for photodynamic therapeutical applications.