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Gunasekar, Gunniya Hariyanandam,Yoon, Sungho The Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.23
<P>The phenanthroline unit represents one of the most significant ligand frameworks in coordination chemistry. Constructing phenanthroline-based porous organic polymers with nonreactive functional groups in the polymer skeleton is a very challenging goal in the field of heterogeneous catalysis, because it would offer a novel platform for doping molecular catalytic modules and generating single-site, stable, and porous heterogeneous catalytic entities for a wide range of catalytic applications. In this regard, a unique strategy to construct phenanthroline-based porous organic polymer (phen-POP) without other reactive/coordinating functional groups in the polymer skeleton has been designed for the first time, and synthesized <I>via</I> a solvent knitting Friedel-Crafts polymerization method with a high BET surface area of 560 m<SUP>2</SUP> g<SUP>−1</SUP>. The well-defined and isolated phen sites of the phen-POP can serve as a platform for immobilizing transition metal catalysts through N-N coordination bonds. The post-synthetic metalation of phen-POP with iridium(iii) chloride afforded the most active (initial turnover frequency of 40 000 h<SUP>−1</SUP>), simple and selective heterogeneous Ir catalyst for the hydrogenation of CO2 to formate. Thus, the work is significant in constructing novel POP-based heterogeneous catalysts for the development of industrially viable hydrogenation catalysts.</P>
Gunasekar, Gunniya Hariyanandam,Jung, Kwang-Deog,Yoon, Sungho American Chemical Society 2019 Inorganic chemistry Vol.58 No.6
<P>Today, one of the most imperative targets to realize the conversions of CO<SUB>2</SUB> in industry is the development of practically viable catalytic systems that demonstrate excellent activity, selectivity, and durability. Herein, a simple heterogeneous Ru(III) catalyst is prepared by immobilizing commercially available RuCl<SUB>3</SUB>·<I>x</I>H<SUB>2</SUB>O onto a bipyridine-functionalized covalent triazine framework, [bpy-CTF-RuCl<SUB>3</SUB>], for the first time. This novel catalyst efficiently hydrogenates CO<SUB>2</SUB> into formate with an unprecedented turnover frequency (38800 h<SUP>-1</SUP>) and selectivity. In addition, the catalyst excellently maintains its efficiency over successive runs and produces a maximum final formate concentration of ∼2.1 M in just 2.5 h with a conversion of 12% in regard to CO<SUB>2</SUB> feed. The apparent advantages of air stability, ease of handling, simplicity, the use of a readily available metal precursor, and the outstanding catalytic performance make [bpy-CTF-RuCl<SUB>3</SUB>] one of the possible candidates for realizing the large-scale production of formic acid/formate by CO<SUB>2</SUB> hydrogenation.</P><P>A simple RuCl<SUB>3</SUB>-incorporated bipyridine-based covalent triazine framework efficiently hydrogenates CO<SUB>2</SUB> to formate with unprecedented turnover frequencies of 38800 h<SUP>−1</SUP> and excellent recyclability.</P> [FIG OMISSION]</BR>
Gunasekar, Gunniya Hariyanandam,Park, Kwangho,Ganesan, Vinothkumar,Lee, Kwangyeol,Kim, Nak-Kyoon,Jung, Kwang-Deog,Yoon, Sungho American Chemical Society 2017 Chemistry of materials Vol.29 No.16
<P>Functionalizing the recently developed porous materials such as porous organic frameworks and coordination polymer networks with active homogeneous catalytic sites would offer new opportunities in the field of heterogeneous catalysis. In this regard, a novel covalent triazine framework functionalized with an Ir(III)-N-heterocyclic carbene complex was synthesized and characterized to have a coordination environment similar to that of its structurally related molecular Ir complex. Because of the strong sigma-donating and poor pi-accepting characters of the N-heterocyclic carbene (NHC) ligand, the heterogenized Ir-NHC complex efficiently catalyzes the hydrogenation of CO2 to formate with a turnover frequency of up to 16 000 h(-1) and a turnover number of up to 24 300; these are the highest values reported to date in heterogeneous catalysis for the hydrogenation of CO2 to formate.</P>
Does hotel attributes impact customer satisfaction: A sentiment analysis of online reviews
Sangeetha Gunasekar,Sooriya Sudhakar 한국마케팅과학회 2019 마케팅과학연구 Vol.29 No.2
User-generated content is a major source of information particularly in tourism industry where consumers seek unbiased and unregulated information. While making their hotel booking decisions, consumers refer to the previous guests’ experiences expressed in the hotel reviews across social media. Studies in the literature have focused on enhancing the understanding of what makes customers satisfied or dissatisfied. They have analyzed the text reviews and the patterns in the overall rating and ranking of the hotels given by hotel guests. While most emerging destinations have been studied in the literature, studies related to India, a fast-growing leisure destination are scant. The present study tries to understand the hotel attributes that contribute towards customer satisfaction or dissatisfaction using online reviews for all hotels of Andaman & Nicobar Islands in India. Among the eight attributes identified from the most frequently used words in the text reviews, the study finds that while the location has a significant probability of increasing the ratings of both highand low-rated reviews, rooms seem to have the most significant impact on lowering the probability of high scores irrespective of positive or negative sentiment review. The study also finds that guests of luxury hotels rate the hotels significantly higher than the guests of midrange and budget hotels.
Chakravarthi, Nallan,Gunasekar, Kumarasamy,Cho, Woosum,Long, Dang Xuan,Kim, Yun-Hi,Song, Chang Eun,Lee, Jong-Cheol,Facchetti, Antonio,Song, Myungkwan,Noh, Yong-Young,Jin, Sung-Ho The Royal Society of Chemistry 2016 ENERGY AND ENVIRONMENTAL SCIENCE Vol.9 No.8
<P>Achieving the state-of-the-art performance of solution processable and flexible organic electronics requires efficient, stable, and cost-effective interfacial layers (ILs). Here, we report an alcohol soluble phosphine oxide functionalized 1,3,5-triazine derivative (PO-TAZ) as an IL, which remarkably tailors the work function of conductors including metals, transparent metal oxides and organic materials, making it an ideal candidate for an interfacial material in organic electronics. Consequently, PO-TAZ thin films enable the fabrication of organic and organic-inorganic (perovskite) solar cells with power conversion efficiencies of 10.04% and 16.41%, respectively, and n-channel organic field-effect transistors with an electron mobility of 8 cm(2) V-1 s(-1). Owing to the low-cost processing associated with PO-TAZ and the tremendous improvement in device performances as compared to the devices without PO-TAZ along with ambient stability, PO-TAZ is a good choice for efficient organic electronics in large area printing processes.</P>
Jiang, Jianwei,Gunasekar, Gunniya Hariyanandam,Park, Sanghyuk,Kim, Sang-Ho,Yoon, Sungho,Piao, Longhai Elsevier 2018 Materials research bulletin Vol.100 No.-
<P><B>Abstract</B></P> <P>Hierarchical ∼10 nm Cu nanoparticle (NP)-aggregated sub-micro cage catalysts (diameter: ∼800 nm) with a hollow interior and porous shell were prepared from SiO<SUB>2</SUB> encapsulated Cu<SUB>2</SUB>O nanoparticle aggregates (NPAs) using a facile and scalable method. The Cu cages were analyzed by field emission-scanning electron microscopy (FE-SEM), energy-dispersed X-ray (EDX), transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction (SAED), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET). Owing to the small primary Cu NPs and characteristic porous shell and hollow interior, the Cu cages showed an extraordinarily high catalytic activity in the reduction of 4-nitrophenol by NaBH<SUB>4</SUB> in aqueous solution. The activity factor (<I>K</I> = 520 s<SUP>−1</SUP> g<SUP>−1</SUP>) is approximately 2.8 times greater than the previous highest <I>K</I> value of unsupported Cu catalysts. In addition, the excellent catalytic activity of the Cu cages in hydrogenation of CO<SUB>2</SUB> to formate, with a TON value of 58 at 200 °C, was comparable to that of various noble metal-supported heterogeneous catalysts and surpassed the vast majority of homogeneous first-row transition metal catalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Synthesizing a challenging structure, hierarchical ∼10 nm Cu NP-aggregated sub-micro cages. </LI> <LI> Cu cages showed an excellent catalytic activity in the reduction of 4-nitrophenol by NaBH<SUB>4</SUB>. </LI> <LI> This is the first report on using a Cu NP-based heterogeneous catalyst for the hydrogenation CO<SUB>2</SUB> to formate. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>