Synthesis, characterization and optoelectronic properties of pyrrolopyrazine based Y-shaped color-tunable dipolar molecules

Meti, Puttavva,Yang, Jung-Won,Jung, Sun Hwa,Gong, Young-Dae Elsevier 2019 Dyes and pigments Vol.161 No.-

<P><B>Abstract</B></P> <P>A regioselective approach for the synthesis of functionalized dipolar Y-shaped chromophores is demonstrated. A series of dipolar pyrrolopyrazine based molecules were prepared in a straightforward manner. The key step in the preparation of the chromophores involves two-fold Sonogashira coupling reaction between the pyrrolopyrazine core and acetylene derivatives. Different electron-donors, including, NH<SUB>2</SUB>, NMe<SUB>2</SUB>, OMe and CF<SUB>3</SUB>, CN acceptors were incorporated into the chromophores. By adjusting the substituents at 2, 3, and 6-position of the pyrrolopyrazine, dipolar tunable molecules with wide emission band are synthesized. The optical, thermal, and electrochemical properties of the materials are analysed and the results are supported with the DFT calculations. The preliminary studies of these engineered Y-shaped molecules indicate their potential as new building blocks in the fields of optoelectronic devices.</P> <P><B>High lights</B></P> <P> <UL> <LI> Pyrrolopyrazine based Y-shaped tunable chromophores were synthesized via two-fold Sonogashira reaction. </LI> <LI> Optical, thermal, electronic, and morphological properties of the chromophore were studied. </LI> <LI> Single crystal XRD shows non planar configuration in chromophore <B>6b.</B> </LI> <LI> DFT calculations were carried out, which are in well agreement with the experimental calculations. </LI> <LI> Chromophores end capped with donor and acceptor show the largest hyperpolarizabilies (249 × 10<SUP>−30</SUP> esu). </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Structure property relationships of tunable donor-acceptor functionalized dipyrrolopyrazine derivative as selective reversible acid base sensor

Meti, Puttavva,Yang, Jung-Won,Gong, Young-Dae Elsevier 2018 Dyes and pigments Vol.156 No.-

<P><B>Abstract</B></P> <P>A practical approach towards the development of organic scaffold for material science application through substituent engineering of dipyrrolopyrazine (DPP) chromophore has been introduced. We describe the synthesis and optoelectronic characterization of DPP-derivatives decorated with Donor and acceptor moieties. This study showed that tailoring of the optical properties in the desired direction can be achieved by differing electron donor and acceptor units attached at C-2 and C-6 position of DPP scaffold. The optical, thermal, and electrochemical properties have been investigated. Chromophores exhibit red-shift in absorption and emission spectra upon treatment with TFA and also exhibit distinct self-assembly behaviour. Morphological characterizations indicate the formation of nanorods and microrods. Optical, thermal and morphological studies indicate its potential application in sensors and other optoelectronic device.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Six DPP based dyes have been synthesized via coupling reaction. </LI> <LI> All the dyes exhibit notable spectra upon treatment with TFA, acting as acid-base sensor. </LI> <LI> Optical, thermal, electronic, and morphological properties have been studied. </LI> <LI> SEM analysis indicates the formation of nanorods and microrods. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Self-assembled organic microfibers and nanofibers of 2,6-diphenyl dihydrodipyrrolopyrazine (DP-DPP) derivatives for optoelectronic applications

Meti, P.,Yang, J.W.,Gong, Y.D. Pergamon Press 2017 Tetrahedron Vol.73 No.35

Microfibers and nanofibers with promising application in optoelectronics are desirable in current material synthesis. Synthetic method has been developed for the preparation of dipyrrolopyrazine derivatives by employing palladium catalysed Buchwald and Sonogashira coupling reactions. A comprehensive study on the synthesis, optical properties, thermal stability and morphology of DP-DPP derivatives 8(a-d) were carried out. Surface morphological analysis showed the formation of microfibers, square facets and nanorods. Electrochemical studies revealed HOMO energy levels in the range of -5.10 to -5.88 eV and LUMO energy levels in the range -2.49 to -3.12 eV. All compounds exhibited a high degree of thermal stability and decomposition temperature of 322-372 <SUP>o</SUP>C. The enhanced air durability and thermal stability combined with good morphology makes DPP as a promising candidate for optoelectronic application.

Synthesis of dipyrrolopyrazine-based sensitizers with a new π-bridge end-capped donor-acceptor framework for DSSCs: a combined experimental and theoretical investigation

Meti, Puttavva,Nagaraju, Goli,Yang, Jung-Won,Jung, Sun Hwa,Gong, Young-Dae The Royal Society of Chemistry 2019 NEW JOURNAL OF CHEMISTRY Vol.43 No.7

<P>The strategy of developing organic dyes with exceptional optical, thermal, and stable photovoltaic properties has attracted substantial attention in the replacement of high-cost traditional dyes in DSSCs. Herein, we synthesized four dyes with a D-π-A configuration in order to study the variation produced in the optical, thermal, redox and photovoltaic properties by substitution of different donors and acceptors in the dipyrrolopyrazine (DPP) system. These push-pull systems are based on a pyrrolopyrazine spacer, end-capped with donors (<I>N</I>,<I>N</I>-dimethylamine, and thiophene) and acceptors (pyridine, -COOH, and -CN). The multidisciplinary study concerning the optical, thermal, redox, and photovoltaic characterization of the dyes reveals that compound 3a exhibits the best overall conversion efficiency as a sensitizer in TiO2 dye sensitized solar cells. The theoretical calculations together with experimental data allow us to quantify the charge transfer character of dyes.</P>

Electro-Catalytic Behavior of an Antiarrhythmic Drug, Procainamide and its Electro-Analytical Applications

Abbar, Jyothi C.,Meti, Manjunath D.,Nandibewoor, Sharanappa T. The Korean Electrochemical Society 2018 Journal of electrochemical science and technology Vol.9 No.4

The electrocatalytic oxidative behavior of an antiarrhythmic drug, procainamide hydrochloride (PAH) at the gold electrode surface has been examined using different voltammetric methods like cyclic, linear-sweep and differential pulse voltammetry. Voltammograms obtained in this study reveal that the electrode exhibit excellent electrocatalytic activity towards oxidation of the drug. The parameters that can affect the peak current at different pH, scan rate and concentration were evaluated. The number of electrons transferred was calculated. The current displayed a wide linear response ranging from 0.5 to $30.0{\mu}M$ with a limit of detection of 56.4 nM. The impact of potential interfering agents was also studied. The electrode displayed wide advantages such as simple sample preparation, appreciable repeatability, reproducibility and also high sensitivity. Furthermore, the feasibility of the proposed method was successfully demonstrated by determining PAH in the spiked human biological sample.

Complementary feeding practices and nutritional status of children 6-23 months old

Aripin Ahmad,Siti Madanijah,Cesilia Meti Dwiriani,Risatianti Kolopaking 한국영양학회 2018 Nutrition Research and Practice Vol.12 No.6

BACKGROUND/OBJECTIVES: The 6-23 months for infants is the longest period in the “first 1,000 days” of life. This period is very important for child development, so complementary feeding (CF) practices should be optimized to maximize children’s potential for growth and development. The aim of this study was to analyze the CF practices and nutritional status of children aged 6-23 months. SUBJECTS/METHODS: For this cross-sectional study, 392 children aged 6-23 months were selected using stratified random sampling. Socio-demographic data were collected through interviews. CF practices, collected by interviews and repeated 24-hour food recall method, were the timely introduction of CF, minimum meal frequency, dietary diversity and minimum acceptable diet, consumption food rich in proteins and vitamin A. Nutritional status was assessed using the indicators of underweight, wasting and stunting. To analyze the association between socio-demographic indicators and CF with nutritional status, the chi-square test with a confidence interval of 95% was used. RESULTS: Results showed that 39% were exclusively breastfed, only 61% received prolonged breastfeeding and 50% received timely introduction of CF. Minimum meal frequency was met by 74% of subjects, but dietary diversity and minimum acceptable diet were only realized in 50% and 40% of the children, respectively. The prevalence of underweight, wasting, and stunting were 26%, 23%, and 28%, respectively. Age of the child, birth order, birth weight, parents’ education level, family size and incidence of fever and diarrhea during the previous two weeks were associated with underweight, while child’s birth order, fathers’ education level, mother’s age, family size, completion of the age-appropriate vaccination and fish consumption frequency were associated with wasting. Age of the child, incidence of fever and acute respiratory infection, and fortified food consumption were associated with stunting. CONCLUSIONS: Suboptimal CF practices and high prevalence of underweight, wasting and stunting were found among children aged 6-23 months old in Aceh. These results highlight the need to improve CF and nutritional status.