Sapana Jadoun

Microwave-assisted green synthesis of some nanoconjugated copolymers: characterisation and fluorescence quenching studies with bovine serum albumin

Copolymerization is an effective technique to design conjugated polymers with properties higher than individual homopolymers, as the composition and the desired chemical properties can be controlled by the judicious choice of co-monomers and polymerization techniques. With a view to explore the influence of microwave-assisted copolymerization on the spectral and fluorescence properties of some functionalized monomers, the present work reports for the first time, the synthesis of conjugated copolymers of poly(1-naphthylamine), poly(o-phenylenediamine), and poly(o-anisidine) under microwave irradiation. Fourier transform infrared spectroscopy confirmed random copolymerization, while ultraviolet-visible studies revealed the variation in polaronic states upon copolymerization. High crystallinity was achieved through the formation of a distorted orthorhombic lattice and controlled morphology via microwave-assisted synthesis which was confirmed by X-ray diffraction and transmission electron microscopy analysis. This behaviour was explained on the basis of variable orientations adopted by the conducting polymer chains. A water soluble homopolymer and a copolymer were tested for the deactivation of bovine serum albumins fluorescence and the former was found to effectively quench the fluorescence emission of the latter. Quenching occurred through formation of an intermolecular complex and was initiated by photoinduced electron transfer and was observed to be static in nature. The quenching rate constant, kq, for POPD and POPD-co-PNA was found to be 1.08 × 1014 L M−1 s−1 and 2.0 × 1014 L M−1 s−1, revealing a much higher quenching rate constant kq for the copolymer than the homopolymer. Likewise, the binding constants, Ka, for a homopolymer and a copolymer were found to be 3.98 × 106 L mol−1 and 1.26 × 107 L mol−1, revealing a much higher binding constant for the copolymer POPD-co-PNA than the homopolymer POPD. Confocal microscopy revealed widely distributed binding of the copolymer with the tryptophan residues in the protein scaffold. These results reveal that the copolymer holds potential for use in bioimaging and also as a protein sensor.

Tuning the spectral, thermal and fluorescent properties of conjugated polymers via random copolymerization of hole transporting monomers

With the aim to design conjugated copolymers of hole generating monomers, the present paper reports for the first time, ultrasonic-assisted synthesis of poly(o-phenylenediamine) and polycarbazole using different molar ratios of the two monomers. The copolymerization was established by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, ultraviolet-visible spectroscopy and differential theromogravimetric analysis while the morphology was investigated using X-ray diffraction and transmission electron microscopy studies. The copolymer composition was confirmed by nuclear magnetic resonance spectroscopy which matched with the molar feed ratio. Reactivity ratios (r1 and r2 values) confirmed random copolymerization. Infrared spectra revealed that values increased with the increase in the poly(o-phenylenediamine) units. Cyclic voltammetry also confirmed copolymerization. Oxidation and reduction potentials corresponding to the redox peaks of o-phenylenediamine and carbazole copolymers of different composition were close to each other, but fairly different from those of the pure polymers. Redox current densities of copolymers of different compositions were found to vary with the composition. Ultraviolet-visible spectroscopy studies also revealed a progressive change in the optical properties as the copolymer composition changed from 90–10% polycarbazole. X-ray diffraction studies showed morphology of the copolymers to be an intermediate between PCz and POPD where PCz polymer chains appeared least compact and the poly(o-phenylenediamine) chains appeared more close and compact. Fluorescence studies confirmed that as the ratio of poly(o-phenylenediamine) in the copolymer increased from 30–90%, quantum yield increased from 0.27–0.37. Thermogravimetric analysis and differential theromogravimetric studies confirmed copolymerization of the monomers and showed two types of copolymer complexions which were consistent with the experimentally determined copolymerization ratio.

Tuning the spectral, morphological and photophysical properties of sonochemically synthesized poly(carbazole) using acid Orange, fluorescein and rhodamine 6G.

The lifetimes and quantum yields of organic dyes are widely investigated due to their potential application in organic light emitting diodes (OLEDs). With a view to explore the possibility of enhancing the fluorescent properties of organic conjugated polymers such as polycarbazole, the present preliminary study reports for the first time, dye modification of polycarbazole using as acid orange (AO), fluorescein (Fluo) and Rhodamine 6G (R6G) for improving its fluorescence properties. The modification of PCz via doping was confirmed by FTIR, UV-visible, XRD and TEM analyses. The fluorescence studies and confocal microscopy were carried out both in solution and solid states to investigate the behavior of the dye modified PCz. Doping was found to be governed by the chemical structure of the dye. PCz-AO revealed intense doping which was confirmed by FTIR and UV-visible studies. PCz-Fluo and PCz-R6G exhibited the highest quantum yield and fluorescence emission in the solid state. Hence, by tailoring the structure of these conjugated polymers, stable fluorescence emitting materials can be designed for their potential application in OLEDs.

Sonolytic doping of poly(1-naphthylamine) with luminol: influence on spectral, morphological and fluorescent characteristics

AbstractDoping is one of the most facile techniques adopted to improve the optoelectronic properties of conducting polymers. The present preliminary work reports, for the first time, chemical doping of poly(1-napthylamine) (PNA) with (5-amino-2,3-dihydro-1,4-phthalazine-dione) widely known as luminol, to study its influence on the spectral, morphological, and optical properties of PNA. PNA was doped with luminol in acidic, basic, and neutral media. The neutral polymer and its doped forms were characterized using FTIR, UV-visible, XRD, and TEM analyses. FTIR studies confirmed doping of PNA by luminol, while UV-visible and fluorescence studies revealed the changes in the electronic structure of PNA upon doing. Confocal microscopy revealed intense red emission confirming that the polymers could be used for near infrared fluorescence imaging. Graphical abstractSonolytic doping of poly(1-naphthylamine) using luminol

A short review on the synthesis, characterization, and application studies of poly(1-naphthylamine): a seldom explored polyaniline derivative

Poly(1-naphthylamine) (PNA) has been one of the seldom explored polyaniline (PANI) derivatives in spite of its versatile electrochromic and optoelectronic properties. The present review summarizes, for the first time, synthesis, characterization, and application studies related to poly(1-naphthylamine) as well as its copolymers, blends, and nanocomposites that have been carried out during the past two decades. Details about the chemical as well as electrochemical techniques used for the synthesis of this polymer are provided along with various procedures adopted to improve its processibility via formulation of copolymers, blends, and nanocomposites. Recent studies dealing with the potential applications of this polymer in the field of catalysis and coatings are also evaluated.

Microwave-assisted solid state intercalation of Rhodamine B and polycarbazole in bentonite clay interlayer space: structural characterization and photophysics of double intercalation

Intercalation of organic moieties in layered double hydroxides/clays has been used to obtain various hybrid compounds with enhanced properties and wide ranging applications. Most intercalation of organic moieties into clays is performed in aqueous media through the mechanism of ion exchange. However, intercalation of organic moieties in clays can also occur through diffusion in the solid state if the process is carried out under microwave irradiation. We have attempted in this study to investigate, for the first time, the double intercalation of two organic moieties, Rhodamine B and polycarbazole, in bentonite clay galleries in the solid state through microwave irradiation at controlled temperatures of 30 °C and 50 °C. Polycarbazole was simultaneously polymerized from carbazole under the above experimental conditions. Optical micrography revealed the intercalation of both Rhodamine B and polycarbazole. Carbon, hydrogen, and nitrogen (CHN) analysis quantitatively indicated the intercalated amounts of the two moieties. X-ray diffraction analysis showed the orientations of the Rhodamine B and polycarbazole molecules and how the higher loading of Rhodamine B and polycarbazole distorts the lattice of the bentonite clay. Confocal microscopy distinctly showed the presence of both Rhodamine B and polycarbazole in the interlayer space. Quantum yield (Φ) values more explicitly demonstrated the effect of increasing the amounts of Rhodamine B and polycarbazole in the clay galleries. The fluorescence lifetimes (τf), intrinsic fluorescence decay constants (k°f) and internal conversion constants (kIC) showed consistent and distinct values for the double intercalation variables. The symmetrical configuration of Rhodamine B molecules was deformed by distortion of the dihedral angles of the pendant phenylene and carboxylate groups in the clay galleries. These distortions created fluorescence states with different decay times and energies.

Influence of Luminol Doping of Poly(o-phenylenediamine) on the Spectral, Morphological, and Fluorescent properties: A Potential Fluorescent Marker for Early detection and Diagnosis of Leishmania donovani

There has been a steady progress in the development of doped conjugated polymers to remarkably improve their photo physical properties for their application as biomarkers. With a view to enhance the spectral, morphological, and photo physical properties of poly(o-phenylenediamine) (POPD), the present work reports the synthesis of poly(o-phenylenediamine) and doping of this polymer using luminol. The formation of luminol-doped POPD was confirmed by infrared and ultraviolet-visible spectroscopies and X-ray diffraction studies. The energy band gap values and oscillator strength of luminol in acidic, basic, and neutral media were computed by density functional theory calculations using the B3LYP/6-31G (d) basis set and were compared with experimental data. The luminol doped POPDs show significant in vitro anti-leishmanial activity. Live cell imaging also proved that these molecules bind with the organelle of Leishmania also. These luminol doped POPDs were found non-toxic at the used concentrations on THP-1 derived human macrophage cells through methyl tetrazolium (MTT) assay. The results revealed that luminol doped POPDs were potentially non-toxic to human cells though exhibited immense potential to be used as a fluorescent marker to label Leishmania donovani for diagnostic and other studies.

Luminol modified polycarbazole and poly( o -anisidine): Theoretical insights compared with experimental data

With the aim to explore the effect of luminol as a multifunctional dopant for conjugated polymers, the present study reports the ultrasound-assisted doping of polycarbazole (PCz) and poly(o-anisidine) (PAnis) with luminol in basic, acidic and neutral media. The synthesized homopolymers and luminol doped polymers were characterized using FT-IR, UV-visible and XRD studies while the photo-physical properties were investigated via fluorescence spectroscopy. Density functional theory (DFT) calculations were performed to get insights into the structural, optical, and electronic properties of homopolymers of polycarbazole (PCz) and poly(o-anisidine) (PAnis). Vibrational bands B3LYP/6-311G (d,p) level, UV-vis spectral bands and electronic properties such as ionization potentials (IP), electron affinities (EA) and HOMO-LUMO band gap energies of the homopolymers and doped polymers were calculated and compared. Results revealed that luminol doped polymers showed different photo-physical characteristics in acidic, basic and neutral media which could be tuned to obtain near infrared (NIR) emitting polymers.

Silver ferrite and cobalt ferrite dispersed castor oil polyurethane nanocomposites: Quenching studies of bovine serum albumin

ABSTRACT The use of renewable resource is a strategic opportunity to meet growing demands of eco-friendly materials. The present study reports the synthesis of castor-oil-based polyurethane (COPU), and its nanocomposites with CoFe2O4 and AgFeO2 via sonication technique. Formation of the nanocomposite was confirmed by IR analysis while UV–visible studies revealed encapsulation of the ferrite particles by COPU. The interaction between COPU, AgFeO2, CoFe2O4, and their nanocomposites with bovine serum albumin (BSA) was also investigated by fluorescence spectroscopy which revealed static quenching of BSA through complex formation. The quenching rate for COPU was determined to be 1.98 × 104 LM−1 while for pure CoFe2O4 and AgFeO2, it was found to be 3 × 104 LM−1 and 3.2 × 104 LM−1, respectively. The interaction of BSA particularly with silver and cobalt ferrite nanoparticles within COPU matrix was found to be promising. It was found that by controlling the loading of ferrite in COPU matrix, desired binding could be achieved. GRAPHICAL ABSTRACT

Tuning the optical properties of poly(o-phenylenediamine-co-pyrrole) via template mediated copolymerization

Abstract Tailoring of conjugated monomers via copolymerization is a facile method to obtain tunable spectral, morphological and optical properties. To investigate the effect of copolymerization of pyrrole with o-phenylenediamine on the optoelectronic properties of the synthesized copolymers, the present work reports the synthesis of copolymers of o-phenylenediamine with pyrrole with varying mol ratios via chemical polymerization in methylene blue (MB) medium. Copolymerization was confirmed by Fourier transform infrared spectroscopy and ultraviolet-visible studies. Ultraviolet-visible spectroscopy revealed variation in the optical properties with the change in the monomer ratio. Fluorescence studies showed that the copolymer containing 80% poly(o-phenylenediamine) revealed highest quantum yield among all the copolymers. The emission color could therefore be tuned by careful selection of narrow band co-monomers, which could help in designing tunable fluorescence emitting materials for potential application in OLED devices.