Editorial pubs.acs.org/journal/ascecg
Festschrift in Honor of Rajender S. Varma pioneered the application of electromagnetic waves such as microwave1 and ultrasound expedited systems, which were adopted around the globe.2 His ventures in the solvent-free preparation of ionic liquids3 and their exploration as catalysts for utilization of carbon dioxide4 led to fruitful results in 2005 (see his collection of papers). These have become areas of intense research today. Raj has had many seminal contributions in the green chemistry area. The single most impactful contribution has been in the area of alternative energy input into chemical reactions under a variety of eco-friendly conditions, most importantly utilizing microwave (MW) irradiation.1 Raj pioneered MW-assisted chemistry under solvent-free conditions in the early 1990s using a simple household microwave oven, at a time when dedicated MW equipment was just appearing. He has since published more than 125 peer-reviewed papers on this subject, using benign solvents such as water5 and polyethylene glycol6 to assemble a wide variety of nitrogen and oxygen heterocyclic systems and eco-friendly chemical transformations. Today, it is difficult to find a pharmaceutical company in the world that does not use MW chemistry as an enabling technology in their drug discovery programs to generate libraries of “lead” compounds.7 Recently, using dedicated laboratory MW systems and learning from nature, Raj has simplified the generation of arrays of nanoparticles via biomimetic pathways. His pioneering work has resulted in the most sustainable production of nanomaterials known to date;8 this activity has spurred countless advances in the production and use of these materials, especially as nanocatalysts.9 His approach to mimic nature has led to the synthesis of nanometal/nanometal oxide/nanostructured composites and their stabilization. It has led to the utilization of natural biorenewable resources in nanoparticle synthesis, such as plant extracts and polyphenolic antioxidants from various sources,10 biodegradable polymers, such as cellulose,11 reducing sugars,12 and agricultural residues (beet juice),13 waste material (red grape pomace)14 from winery waste, and glycerol (biodiesel byproduct).15 His work avoids the use of toxic agents, such as borohydrides, hydrazines, or polyvinylpyrolidone, producing them in the matrix in which they are to be used thus reducing the risk of exposure or eliminating the use and generation of hazardous substances normally used. Notable among these advances are nanoparticles with a magnetic core,16 a property that renders them recoverable for reuse. Beneficial consequences of these materials in the synthesis and greener remediation have been quite impressive on an international level, as evidenced by innumerable research projects and companies that have grown out of his research or used his technology. The functionalization of the surfaces of nanosized magnetic materials provides a quasi-homogeneous phase and acts as a bridge between heterogeneous and homogeneous catalysis thus retaining the relative advantages of both of the catalysis systems,17 with their
I
am very pleased to present the inaugural Festschrift of ACS Sustainable Chemistry & Engineering as a virtual special issue {http://pubs.acs.org/page/ascecg/vi/varma-tribute.html} that honors Dr. Rajender (Raj) S. Varma of the United States Environmental Protection Agency (U.S. EPA) on the occasion of his 65th birthday. Raj was born in New Delhi, India, and being a child of itinerant defense personnel, he was brought up in diverse parts of the country. He received his B.Sc. from Punjab University in 1970 and M.Sc. in Chemistry from Kurukshetra University in 1972, where his interest in chemistry was kindled by a great teacher, Prof. S. M. Mukherjee. He received a Ph.D. in organic (natural products) chemistry from the University of Delhi in 1976, under the tutelage of Professors T.R. Seshadri and M.R. Parthsarathy, exploring secondary metabolites from plant sources. Subsequently, he explored natural biopolymer, cellulose, and delignification processes at the Norwegian Institute of Technology, Trondheim, Norway (1977−1978). He was a senior research assistant in Robert Robinson Laboratories, University of Liverpool, United Kingdom (1979−1982) and a postdoctoral fellow at the University of Tennessee, Knoxville (1983−1985). His academic career started in 1985 at Baylor College of Medicine, Center of Biotechnology, Woodlands, Texas, with a concurrent senior scientist position at the neighboring Technology Development Laboratory of the Houston Advanced Research Center (HARC). The exciting interdisciplinary research led him to explore applied applications at the interface of chemical science with biology, solid-state chemistry, and bioelectronics. He also held a research professorship (1996−1999) at Sam Houston State University, Huntsville, Texas, prior to joining the U.S. EPA’s Sustainable Technology Division, National Risk Management Research Laboratory, in Cincinnati, Ohio, as a senior scientist. Currently, he is also a visiting scientist of the department of physical chemistry at Palacky University, Olomouc, Czech Republic. Raj always had an abiding interest in simplifying chemical processes and essentially practiced green chemistry in the early 1990s when this term and its principles were just emerging. He examined solvent-free chemistry on mineral supports and © 2016 American Chemical Society
Received: February 3, 2016 Published: March 7, 2016 640
DOI: 10.1021/acssuschemeng.6b00254 ACS Sustainable Chem. Eng. 2016, 4, 640−642
ACS Sustainable Chemistry & Engineering
Editorial
outstanding contribution to Retina Research, The Retina Research Foundation, Houston, Texas, United States. On a personal note, it is great honor to associate with Raj as a friend and colleague. I wish him always the very best as he continues to have a steadfast enthusiasm for research in the coming years. I gratefully thank Raj’s many colleagues and friends from various institutions all around the world for contributing to this issue in his honor; they are founding members of the green chemistry networks on various continents and winners of notable green chemistry awards. A wide-ranging coverage of emerging topics have been embraced in this virtual issue, namely, the usage of waste biomass-derived chemicals; solvent-free reactions; process intensification in continuous flow processes; unique and advantageous use of ionic liquids and water as a reaction medium; alternate energy input systems to enhance chemical reactions using solar, photochemical, mechanochemical, and microwave energy; carbon dioxide capture; bioinspired routes to nanomaterials; sustainable utility of magnetic nanocatalysts in chemical synthesis; and environmental remediation using earth-abundant higher valent iron-based materials. Some of the notable and persuasive papers authored by Raj Varma, published by the American Chemical Society, are also highlighted in this virtual issue.3−5,22−31
recycling and recovery using an external magnet being a major advantage. Magnetically separable materials not only recover and identify the dispersed nanomaterials in the environment, but C-, N-, and S-doped18 TiO2 exhibited a remarkable photodegradation activity, including for cyanobacterial toxins found in water (algal blooms).19 This research has lately been extended to “doped” graphitic carbon nitrides20,21 that can be easily prepared from urea. He has 14 United States patents and more than 430 peerreviewed papers, 6 books, 26 book chapters, and 3 encyclopedia contributions, mainly dealing with green chemistry advancements (H-Index 83, Google scholar: https://scholar.google. com/citations?user=kzbCKOQAAAAJ&=en and Research Gate: https://www.researchgate.net/profile/Rajender_Varma/ info). Importantly, his enthusiasm for green chemistry research has influenced a new generation of scientists that is following in his footsteps. He has been invited to present plenary and invited keynote lectures at international conferences and educational and research institutions, and he has traveled to almost every region of world. His enduring passion to stimulate the younger generation, especially in underdeveloped nations, takes him to remote areas of the world as a private citizen. He is serving the community as a member of the editorial boards of a number of scientific publications such as ACS Sustainable Chemistry & Engineering (American Chemical Society); Environmental Science: Nano (Royal Society Chemistry); International Journal of Green Nanotechnology (Taylor and Francis); Organic and Medicinal Chemistry Letters (Springer-Verlag, Heidelberg, Germany); Applied Sciences, MDPI AG Basel, Switzerland; and Current Organic Chemistry, Current Green Chemistry, Current Organocatalysis, and Current Microwave Chemistry (Bentham Science), among others. Because of his numerous esteemed accomplishments in research and impressive contributions to the community, the U.S. EPA has given him a number of awards, including an Office of Research and Development (ORD) Sustainability Award (2015) for “Sustainable Strategies for Risk Reduction in Nanotechnology: Application in Chemical Catalysis and Environmental Remediation”; a U.S. EPA Silver Medal for Superior Service for outstanding scientific and leadership contributions establishing the U.S. EPA as a pioneering organization in the area of green chemistry (2013); several National Risk Management Research Laboratory Awards, including Systems Approach to Sustainable Solutions (2012), Environmental Solutions (2010), and Visionary of the Year Award − Green Technology for the Environment(2009); numerous Science and Technology Achievement Awards on varied topics, such as Exceptional Technical Achievement in Developing a Microwave Technology for Greener Chemical Processing in Water, Designing a Process for Converting Greenhouse Gas, CO2, to Cyclic Carbonates in Non-Volatile Ionic Liquid Solvents, Developing a Novel Approach for Greener Production and Safer Use of Noble Nanometals and Metal Oxides (2007), and Greener Strategies for Chemical Synthesis (2003). During prior years (1996−2002), Raj was also honored by international organizations for his outstanding lecturing and research. These awards are Themis Medicare Chemcon Distinguished Speaker Award from Indian Institute of Chemical Engineers (I.I.Ch.E.); Prof. S. Ramaseshan Distinguished Lecture Award, Astrazeneca Research Foundation; Prof. R. A. Rajadhyaksha Distinguished Speaker Award, University Department of Science and Technology, University of Mumbai, Mumbai, India; and Marjorie W. Margolin Prize for
Virender K. Sharma
■
Department of Environmental and Occupational Health, School of Public Health, Texas A&M University, College Station, Texas 77840, United States
AUTHOR INFORMATION
Notes
Views expressed in this editorial are those of the author and not necessarily the views of the ACS. The authors declare no competing financial interest.
■
REFERENCES
(1) Varma, R. S. Solvent-free organic syntheses. using supported reagents and microwave irradiation. Green Chem. 1999, 1, 43−55. (2) Varma, R. S. Journey on greener pathways: from the use of alternate energy inputs and benign reaction media to sustainable applications of nano-catalysts in synthesis and environmental remediation. Green Chem. 2014, 16, 2027−2041. (3) Namboodiri, V. V.; Varma, R. S. Solvent-Free Sonochemical Preparation of Ionic Liquids. Org. Lett. 2002, 4, 3161−3163. (4) Kim, Y.-J.; Varma, R. S. Tetrahaloindate(III)-Based Ionic Liquids in the Coupling Reaction of Carbon Dioxide and Epoxides To Generate Cyclic Carbonates: H-Bonding and Mechanistic Studies. J. Org. Chem. 2005, 70, 7882−7891. (5) Ju, Y.; Varma, R. S. Aqueous N-Heterocyclization of Primary Amines and Hydrazines with Dihalides: Microwave-Assisted Syntheses of N-Azacycloalkanes, Isoindole, Pyrazole, Pyrazolidine, and Phthalazine Derivatives. J. Org. Chem. 2006, 71, 135−141. (6) Namboodiri, V. V.; Varma, R. S. Microwave-accelerated Suzuki cross-coupling reaction in polyethylene glycol (PEG). Green Chem. 2001, 3, 146−148. (7) Kappe, C. O.; Kumar, D.; Varma, R. S. Microwave-Assisted HighSpeed Parallel Synthesis of 4-Aryl-3,4-dihydropyrimidin-2(1H)-ones using a Solventless Biginelli Condensation Protocol. Synthesis 1999, 1999, 1799−1803. (8) Varma, R. S. Greener approach to nanomaterials and their sustainable applications. Curr. Opin. Chem. Eng. 2012, 1, 123−128. (9) Polshettiwar, V.; Varma, R. S. Green chemistry by nano-catalysis. Green Chem. 2010, 12, 743−754.
641
DOI: 10.1021/acssuschemeng.6b00254 ACS Sustainable Chem. Eng. 2016, 4, 640−642
ACS Sustainable Chemistry & Engineering
Editorial
(10) Nadagouda, M. N.; Varma, R. S. Green synthesis of silver and palladium nanoparticles at room temperature using coffee and tea extract. Green Chem. 2008, 10, 859−862. (11) Nadagouda, M. N.; Varma, R. S. Synthesis of Thermally Stable Carboxymethyl Cellulose/Metal Biodegradable Nanocomposites for Potential Biological Applications. Biomacromolecules 2007, 8, 2762− 2767. (12) Nadagouda, M. N.; Varma, R. S. Microwave-Assisted ShapeControlled Bulk Synthesis of Noble Nanocrystals and Their Catalytic Properties. Cryst. Growth Des. 2007, 7, 686−690. (13) Kou, J.; Varma, R. S. Beet Juice-Induced Green Fabrication of Plasmonic AgCl/Ag Nanoparticles. ChemSusChem 2012, 5, 2435− 2441. (14) Baruwati, B.; Varma, R. S. High Value Products from Waste: Grape Pomace ExtractA Three-in-One Package for the Synthesis of Metal Nanoparticles. ChemSusChem 2009, 2, 1041−1044. (15) Kou, J.; Bennett-Stamper, C.; Varma, R. S. Green Synthesis of Noble Nanometals (Au, Pt, Pd) Using Glycerol under Microwave Irradiation Conditions. ACS Sustainable Chem. Eng. 2013, 1, 810−816. (16) Nasir Baig, R. B.; Varma, R. S. Organic synthesis via magnetic attraction: benign and sustainable protocols using magnetic nanoferrites. Green Chem. 2013, 15, 398−417. (17) Nasir Baig, R. B.; Varma, R. S. Magnetically retrievable catalysts for organic synthesis. Chem. Commun. 2013, 49, 752−770. (18) Virkutyte, J.; Varma, R. S. Synthesis and visible light photoactivity of anatase Ag and garlic loaded TiO2 nanocrystalline catalyst. RSC Adv. 2012, 2, 2399−2407. (19) Pelaez, M.; Baruwati, B.; Varma, R. S.; Luque, R.; Dionysiou, D. D. Microcystin-LR removal from aqueous solutions using a magnetically separable N-doped TiO2 nanocomposite under visible light irradiation. Chem. Commun. 2013, 49, 10118−10120. (20) Verma, S.; Nasir Baig, R. B.; Han, C.; Nadagouda, M. N.; Varma, R. S. Magnetic graphitic carbon nitride: its application in the C−H activation of amines. Chem. Commun. 2015, 51, 15554−15557. (21) Verma, S.; Nasir Baig, R. B.; Han, C.; Nadagouda, M. N.; Varma, R. S. Oxidative esterification via photocatalytic C−H activation. Green Chem. 2016, 18, 251−254. (22) Gawande, M. B.; Shelke, S.; Zboril, R.; Varma, R. S. MicrowaveAssisted Chemistry: Synthetic Applications for Rapid Assembly of Nanomaterials and Organics. Acc. Chem. Res. 2014, 47, 1338−1348. (23) Hebbalalu, D.; Lalley, J.; Nadagouda, M. N.; Varma, R. S. Greener Techniques for the Synthesis of Silver Nanoparticles Using Plant Extracts, Enzymes, Bacteria, Biodegradable Polymers, and Microwaves. ACS Sustainable Chem. Eng. 2013, 1, 703−712. (24) Nasir Baig, R. B.; Varma, R. S. Magnetic Silica-Supported Ruthenium Nanoparticles: An Efficient Catalyst for Transfer Hydrogenation of Carbonyl Compounds. ACS Sustainable Chem. Eng. 2013, 1, 805−809. (25) Nadagouda, M. N.; Speth, T.; Varma, R. S. Microwave-Assisted Green Synthesis of Silver Nanostructures. Acc. Chem. Res. 2011, 44, 469−478. (26) Polshettiwar, V.; Baruwati, B.; Varma, R. S. Self-Assembly of Metal Oxides into Three-Dimensional Nanostructures: Synthesis and Application in Catalysis. ACS Nano 2009, 3, 728−736. (27) Polshettiwar, V.; Varma, R. S. Microwave-Assisted Organic Synthesis and Transformations using Benign Reaction Media. Acc. Chem. Res. 2008, 41, 629−639. (28) Nadagouda, M. N.; Varma, R. S. A Greener Synthesis of Core (Fe, Cu)-Shell (Au, Pt, Pd, and Ag) Nanocrystals Using Aqueous Vitamin C. Cryst. Growth Des. 2007, 7, 2582−2587. (29) Ju, Y.; Kumar, D.; Varma, R. S. Revisiting Nucleophilic Substitution Reactions: Microwave-Assisted Synthesis of Azides, Thiocyanates, and Sulfones in an Aqueous Medium. J. Org. Chem. 2006, 71, 6697−6700. (30) Varma, R. S.; Naicker, K. P. The Urea−Hydrogen Peroxide Complex: Solid-State Oxidative Protocols for Hydroxylated Aldehydes and Ketones (Dakin Reaction), Nitriles, Sulfides, and Nitrogen Heterocycles. Org. Lett. 1999, 1, 189−191.
(31) Varma, R. S.; Dahiya, R. An Expeditious and Solvent-Free Synthesis of 2-Amino-Substituted Isoflav-3-enes Using Microwave Irradiation. J. Org. Chem. 1998, 63, 8038−8041.
642
DOI: 10.1021/acssuschemeng.6b00254 ACS Sustainable Chem. Eng. 2016, 4, 640−642
