Ramesh L Gardas

Indian Institute of Technology Madras | IIT Madras · Department of Chemistry

This book informs readers about recent advances in graphene carbocatalysis encapsulating the current developments in the syntheses, properties, characterizations, functionalization and catalytic applications of graphene, its derivatives and composites. It serves as a comprehensive primary reference book for chemistry and engineering students who ar...

The present study deals with understanding the impact of different surfactants with nano silica based ester fluid on its electrical and rheological properties. The stability of nanofluid is of prime concerns, which is achieved by the inclusion of ionic and non-ionic surfactants viz. cetyl trimethyl ammonium bromide (CTAB), oleic acid and Span-80. I...

The anthropogenic carbon dioxide (CO2) emission into the atmosphere causes environmental concern that leads to drastic climate change due to global warming. The capture of CO2 from flue gases and utilization into value-added products is a viable method for reducing CO2 emissions. Amine-based solvents have been widely employed for the separation of...

Diethylenetriamine (DETA) based protic ionic liquids (ILs) containing different carboxylate as anions have been synthesized and characterized by using NMR, ATR-FTIR, and mass spectroscopic techniques. The alkyl chain of carboxylate anion varied from formate (For) to octanoate (Oct). The synthesized DETA based ILs were subjected to CO2 absorption st...

Ionic liquids are proven to be environmentally greener solvents for various applications due to their enormous properties. Over the last decade, room temperature ionic liquids (RTILs) have gained traction as a potential alternative in nuclear fuel cycle applications. RTILs are being investigated as possible molecular diluent alternatives in the sep...

Herein, a solvent-free synthesis of 5-bromothiophene based 3,4-dihydropyrimidin-2-(1H)-(thi)ones was explored. The main advantages of this study are that pure products are readily obtained through an easy workup and without using any separation technique and in good yields (66-80% yield), All the synthesized products were characterized by ¹H and ¹³...

This study reports the effect of adding silver sulfide to mineral oil and mixed fluid on their static electrification and visco-elastic properties. The flow electrification studies indicate an increase in streaming current for higher silver sulfide concentration with the hysteresis pattern indicating a higher current during the decrement of disc ve...

This paper demonstrates the excess molar properties: excess molar volumes VmE and excess isentropic compressibilities Ks,mE of aqueous binary mixtures of PEGylated DESs at T = (293.15 323.15) K and at atmospheric pressure. The DESs were prepared from combination of Tetrabutylammonium bromide/Benzyltributylammonium chloride as HBA with Polyethylene...

In modern green chemistry, Deep eutectic solvents (DESs) have gain appreciable recognition as an analogues of ionic liquids (ILs) due to inexpensive and easy to handle preparation method. DESs exhibit similar physiochemical properties to ILs and considered as a suitable alternative to volatile organic solvents. In present study, DESs were formulate...

Cationic amphiphiles belong to the large as well as assorted category of antimicrobial agents, which has emerged as a sizzling topic of discussion among scientists these days. These antibacterial molecules are being evaluated preclinically and clinically for the treatment of infection caused by drug-resistant bacteria. Due to the widespread applica...

The density (ρ) and speed of sound (u) of binary solutions containing protic ionic liquids such as N-butyl ethanolammonium acetate [NBEA][Ace] and N-butyl ethanolammonium propionate [NBEA][Pro] with Dimethyl Sulfoxide (DMSO) were determined over a temperature range of (293.15 to 318.15) K at intervals of 5K at 0.1 MPa pressure. The apparent molar v...

Ionic liquids (ILs) have found applications in the pretreatment of waste lignocellulosic biomass by interacting with the carbohydrate molecules present in the biomass materials. Pretreatment is essential before biomass conversion into valuable chemicals, fuels, and many other value-added products. This comparative study mainly focused on the pretre...

Herein, acetic acid mediated multicomponent synthesis of novel 2,4-dimethoxy-tetrahydropyrimido[4,5-b]quinolin-6(7H)-one (2,4-dimethoxy-THPQs) was reported. Single-crystal XRD analysis of four newly developed crystals of 2,4-dimethoxy-THPQs and their DFT study were also reported. The structure of all molecules was optimized using DFT B3LYP/6-31G(d)...

Inclusion complexes formation between γ-cyclodextrin (γ-CD) and three pyridinium-based poly(alkyl ethers) linked dendritic ionic liquids containing ethyl (IL-1), butyl (IL-2) and hexyl (IL-3) substituent were achieved, considering they can act as novel drug delivery vehicles. Possible interaction modes between γ-CD and ionic liquids were analyzed t...

Background Exceptional physicochemical properties of ionic liquids (ILs) enable these molten salts to be called as “designer solvents”. ILs thus have been used for a number of applications ranging from lubricants to heat transfer fluids. Due to the synergistic properties, IL and nanoparticles (NPs) hybrid system called ionanofluid (INF) have shown...

Developing a variety of organic compounds with bright solid-state emission is highly advantageous, provided they exhibit stimuli-responsive properties. Such ‘smart’ materials offer a remarkable role in sensing, digital machinery, material science, and the biomedical field. Taking this into account, two phenothiazines (PT) appended vinyl-linked aryl...

Aqueous biphasic system (ABS), as an efficient separation process, can be applied in the extraction and purification of DNA which is an integral part of life science studies. Ammonium-based ionic liquids (ILs) were synthesized, and ABS formation was evaluated with phosphate buffer [K2HPO4-KH2PO4 (1.82:1.00)] as the second phase forming component. T...

Recently, deep eutectic solvent (DES) or ionic liquid (IL) analogues have been considered as the newest green solvent, demonstrating the potential to replace harsh volatile organic solvents. DESs are mainly a combination of two compounds: hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD), which have the ability to interact through extensiv...

The advancement of unique, organic materials possessing exclusive solid-state photoluminescence properties is in high demand due to their noteworthy contribution to materials chemistry and technology. Considering this, a class of novel scissor shaped phenothiazine (PT) derivatives, named PT-Cn-(Ar)2 where n = 2, 12 and Ar = phenyl, naphthyl, anthra...

Biocatalysis is known to aid the sustainability of chemical process and plays a key role in modern organic synthesis. Nevertheless, toxicity of the solvents employed contributed to the “ungreener” side. Search for alternative solvents to organic solvents were quite successful at the time and that was applied in biocatalysis as well. This chapter di...

This study reports experimental investigations of the effects of different surfactants (CTAB, Oleic acid and Span 80) on silica based synthetic ester nanofluids. The positive and negative potential observed for the ionic (CTAB) and non-ionic surfactant (Span 80) from zeta potential analysis indicates an improved stability. The optimization of nanof...

The present study deals with the characterization of electrical and rheological behaviour of the Synthetic ester fluid incorporated with various concentration of Aluminium nitride (AlN) nanoparticles. Zeta potential measurement has shown an excellent stability of the ester fluid mixed with the nanoparticle. Corona inception voltage (CIV) measured u...

This work reveals that the physicochemical properties such as density, ρ and speed of sound, u for the binary mixtures of N-phenylethanolammonium formate ([NPEA][For]) and N-phenylethanolammonium acetate ([NPEA][Ace] with water and ethanol solvents were experimentally measured for the temperature ranges from 293.15 K to 318.15 K at atmosphere press...

Detailed analysis of volumetric and acoustic properties of the dilute solution of ionic liquids (ILs) and acetonitrile play a significant role in the potential engineering field and process design. Moreover, these studies can provide relevant knowledge about the types and scope of the intermolecular interactions governed between the solute and solv...

Research on host-guest chemistry enhances the bioavailability of the guest molecules by ‘remediation processes. For that purpose, evaluating the physicochemical properties of inclusion complexes (ICs, e.g. β-cyclodextrin as host and an ionic liquid as a guest) is necessary and of value for research in green chemistry. In this work, series of the no...

In this work, N-1 substituted 1,2,4-triazolium-based cation and trifluoromethanesulfonate anion based IL is synthesized and used as a solvent system to stabilize haemoglobin (Hb). The conformational stability of Hb at different concentrations of developed IL was inspected through spectroscopic techniques like UV-Vis, steady-state fluorescence, fluo...

Ionic liquids (ILs) have found applications in the pretreatment of waste lignocellulosic biomass by interacting with the carbohydrate molecules present in the biomass materials. Pretreatment is an essential step prior to biomass conversion into valuable chemicals, fuels, and many other value-added products. This comparative study mainly focused on...

Ionic liquids (ILs) have found applications in the pretreatment of waste lignocellulosic biomass by interacting with the carbohydrate molecules present in the biomass materials. Pretreatment is essential before biomass conversion into valuable chemicals, fuels, and many other value-added products. This comparative study mainly focused on the pretre...

Ionic liquids (ILs) are alternative substances for post-combustion CO2 captures because of their tunable properties are modified in terms of cation and anion alteration. The basicity and fluorination of either cation or anion of the ILs may increases the CO2 sorption affinity. In this study, four 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) based ILs,...

Inclusion complexation is one of the best strategies for developing a controlled release of a toxic drug without unexpected side effects from the very beginning of the administration to the target site. In this study, three benzimidazolium based ionic liquids (ILs) having bromide anion and cation bearing long alkyl chains, hexyl- ([C6CFBim]Br), oct...

The solvation behavior of 1,1,3,3 tetramethylguanidinium [TMG] ionic liquids (ILs) containing different carboxylate anions, octanoate (C8H15O2)⁻, decanoate (C10H19O2)⁻ and laurate (C12H23O2)⁻, in dimethylsulfoxide (DMSO) and dimethylformamide (DMF) are examined through apparent molar properties. In this work, three ILs were chosen as they are proti...

This study explores the transport properties of bis(trifluoromethylsulfonyl)imide-based ionic liquids with a naturally derived (1R,2S,5R)-(−)-menthol moiety in the cationic part. In particular, we investigated the dependence of the dynamic viscosity and electrical conductivity as functions of the alkyl chain length. An important finding of this stu...

Herein, Solvent-free synthesis of 5-bromothiophene based 3,4-dihydropyrimidin-2-(1 H )-thi(ones) was explored. The main advantages of this study are that pure product comes in hand with easy workup and without using any separation technique, a good amount of yield, and formation of product in crude form. We developed a single crystal of 4c , and we...

Global warming due to emission of greenhouse gases, especially carbon dioxide (CO2), has a major impact on climate change. A large number of absorbents were tested for CO2 capturing, and the literature reports suggested that ionic liquids (ILs) showed better performance than conventional absorbents. In recent years, several researchers studied expe...

Polysaccharides are high molecular weight biopolymers composed of repeated monosaccharide units linked via glycosidic bonds. They are the most abundant biopolymers in nature synthesized via the process of photosynthesis using inorganic carbon source (CO2) and water. Polysaccharides provide both structural and food reserve (energy) values. The natur...

New experimental density data in a wide range of temperatures (283–363) K and pressures (0.1–95) MPa is here reported for five protic ILs based on the N,N-diethylethanolammonium ([DEEA]) cation, combined with the following anions: acetate ([Ace]), propanoate ([Prop]), butanoate ([But]), pentanoate ([Pent]) and hexanoate ([Hex]) in a 1:1 acid:base p...

Because of industrialization and modernization, phenomenal changes have taken place in almost all spheres of life. Consequently, the consumption of energy resources and the cases of environmental hazards have risen to an unprecedentedly high level. A development model with due consideration to nature and an efficient utilization of energy sources h...

This study reveals that the effect of anion structures on solvent‐solute interactions by analysis of sophisticated thermophysical properties of ionic liquids (ILs) with molecular solvent. Three imidazolium based ILs (1‐octyl‐3‐methylimidazolium) [Omim][NTf2], [Omim][PF6] and [Omim][SCN] were synthesized, characterized and measured the thermophysica...

Excess volume (VE123) and speed of sound (u123) data of three ternary mixtures of N-methylcyclohexylamine (NMC) (1) + p-xylene (2) + 1-alkanols (C3-C5) were determined as a function of composition at 303.15 K and atmospheric pressure. From the measured data, isentropic compressibility (ks123), deviation in isentropic compressibility (ks'123) and th...

In this study, we report on antiproliferative benzyloxy dihydropyrimidinones (DHPMs) produced by the Biginelli reaction of benzyloxy benzaldehyde, urea, and diverse 1,3‐diones. The reaction was catalyzed by lanthanum triflate and completed within 1–1.5 h, with 74–97% yield. The antiproliferative assay was carried out for all synthesized dihydropyri...

The oxidative removal of methylene blue (MB) from synthetic textile wastewater was evaluated using a combination of persulfate and heterogeneous Fenton-like (PS-HFL) process. During batch experiments, the influential variables, including solution pH, initial MB concentration, reaction time, H2O2, goethite, and PS dose, were assessed. Also, an empir...

As part of sustainable industrial bioprocesses, conversion of xylose from lignocellulosic biomass residues has gained attention and importance over recent decades. Xylitol is one such imperative metabolites which can be obtained in a single step conversion from xylose through enzymatic process employing xylose reductase. Xylose reductase from Debar...

The heterocyclic frameworks (pyrrole, furan, quinolone, indole, oxazole, imidazole, triazole, etc.) represent the key structures of medicinal, pharmaceutical, and biologically important molecules as well as many bioactive natural products, for example, alkaloids and macrolides. Development of greener, efficient, and rapid approaches for the synthes...

Owing to the growing emphasis on development of green and sustainable processes in extraction and separation technologies, interest in ionic liquids (ILs) based aqueous biphasic systems (ABS) has significantly amplified for extraction and separation of value-added compounds. The ability of ILs based ABS to act as alternative solvents for non-biocom...

Physicochemical properties of artisanal refined gasoline (ARG) and regular automotive gasoline (RAG) sampled from the Eastern Obolo Creek and Mkpat Enin, Akwa Ibom State, Nigeria were investigated. This was to compare the physicochemical properties of the two gasoline samples with each other and their compliance with American Society for Testing an...

The academia and chemical industry are actively searching for alternative solvents to meet technology requirements since the most widely used solvents are harmful and volatile. For ionic liquids, there are several advantages over conventionally using organic membrane solvents, including high thermal stability, negligible vapor pressure, low volatil...

In the present work, experimental density (ρ) and speed of sound (u) data for the binary mixtures of benzyl alcohol with acetic acid, propionic acid, and n-butyric acid have been reported over the complete range of mole fraction at 298.15 K ≤ T ≤ 313.15 K. Excess volumes (VE ), excess isentropic compressibilities (κs E ), excess partial molar volum...

The use of hydrophilic zwitterionic compounds (ZI) to act as phase forming components of aqueous biphasic systems (ABS) has been attracting increased interest. Although previous works studied the phase behavior of ZI, there is still a lack of knowledge on the partition behavior of compounds in ZI-based ABS. This work reports a study on the influenc...

Due to the costs involved, the capture of CO2 in post-combustion is not currently seen as economically viable. Aiming at changing the perception of post-combustion CO2 from a costly and non-profitable process to a valuable commodity and fostering the development of the next-generation of technologies, novel solvents and their mixtures have been inv...

Densities (ρ) and speeds of sound (u) of 1-butyl-3-methylimidazolium methyl sulphate, [C4C1im][MeSO4] with acetonitrile (ACN), propionitrile (PCN) and n-butyronitrile (n-BCN) in the complete composition range at temperatures between 298.15 K and 313.15 K with 5 K intervals and atmospheric pressure is reported. Solute-solvent interactions have been...

A one-pot procedure for the preparation of functionalized 1,4-dihydropyridines by three-component reaction using substituted heterocyclic aldehydes, ammonium acetate, and substituted β-ketoesters catalyzed by L-proline was described. Present protocol offers excellent yield up to 92%, flexibility with different substitution, convenient operation, an...

A systematic experimental study of the micellization of ethanolammonium carboxylate surface active ionic liquids (SAILs) in aqueous solutions was performed. The effect of two separate anions having different alkyl chain length, laurate and palmitate on the micellization behavior was studied. The effect of different cationic head groups, n-butyl, te...

The structural variance ability of ionic liquids (ILs) provides an opportunity to fine tune the thermophysical properties for given application. For effective extraction of metal ion from water, the applied ILs should be hydrophobic and preferably containing non fluorinated anions. The hydrophobicity of ILs can be further manipulated by the additio...

In this study, the solvation behaviour of monosaccharide's in aqueous solutions of newly synthesized ionic liquid: cholinium propanoate [Chl][Pro] has been studied at various temperatures and concentrations. The volumetric properties of two monosaccharides (viz. D (+)glucose and D (+)-xylose) were evaluated from density and speed of sound data. App...

Amino acid anion based ionic liquids (ILs) in combination with tetrabutylammonium cation were synthesized and their ability to act as effective phase forming components in aqueous biphasic systems (ABS) was studied. The natural and eco-friendly amino acids have been selected as sources of anions in ILs in order to propose biocompatible ABS. The pha...

In this work, five 1,1,3,3-tetramethylguanidine TMG based ionic liquids (ILs) with [TMG]cations as well as monocarboxylic acid anions {[CH3-(CH2)n−COOH], where n = 2,3, 4, 5 and 6}were synthesized and characterized by 1H-NMR, 13C-NMR and . CO2 absorption capacity was studied for even number carboxylic acid anions [TMG][But], [TMG][Hex] and [TMG][Oc...

The water and soil pollution by pharmaceutical residues is considered one of the major environmental concerns. Most conventional methods adopted for the removal of pharmaceutical wastes are associated with high consumption of energy, time and use of volatile organic solvents. With the focus to propose economically viable and environmentally benign...

The use of β-cyclodextrin(β-CD) as a drug delivery vehicle with amino acid based ionic liquid(AAIL)substituent into eukaryotic cells is well documented and thus increases the bioavailability of diverse therapeutics. Therefore, we have preferred β-CD in our work to stabilize AAILs, which can further be separated in a controlled fashion. AAILs, namel...

In the manoeuvre to achieve desulfurization we have explored various nitro substituted positional isomeric imidazolium based aprotic ionic liquids. Ortho, Meta and para substituted nitro benzyl group aided imidazolium based ionic liquids (ILs) were synthesized and used to understand the extractive desulfurization (EDS) efficiency of fuels. Ionic li...

The molecular interactions of amino acids with the different ionic liquids (ILs) are important in order to study the stability and behavior of the amino acids. In this study, we have examined the interactions of glycine in the aqueous solutions with two aprotic ionic liquids based on cholinium cation, namely, cholinium propanoate [Chl][Pro] and cho...

Ionic liquids (ILs) owing to their unique and tunable physicochemical properties have found profound applications in the biomedical and pharmaceutical field. Since ILs are widely used as solubilizing and stabilizing agents for biomolecules. It is important to explore their effect on proteins. Surface active ionic liquids (SAILs) due to their higher...

Protic Ionic Liquids (PILs) with their labile protons are expected to simultaneously disrupt and exudate lipids from microalgae, crucial for efficient biodiesel production. A survey study with a battery of ten carboxylate PILs with lactam and ammonium cations was conducted with dried and dewatered marine Nannochloropsis oculata and Chlorella salina...

Despite the recent advancements in the field of deep eutectic solvents (DESs), their high viscosity often prevents practical applications. A versatile strategy to overcome this problem is either to add a co-solvent or to confine the DES inside a nanoscaled self-organized system. This work assesses the microstructures of a hydrated and nanoconfined...

Crystallisation of ionic liquids [ILs], is of great interest for determining the crystal structure and molecular interactions. Hydrogen bonding is an important non-covalent interaction, which is related to the properties of ILs. In this context, we have prepared 1,1,3,3-tetramethylguanidine [TMG] based ionic liquids (ILs), with different benzoic ac...

In this work, density (ρ) and speed of sound (u) data were measured for aqueous solutions of two drugs namely Emtricitabine and Lamivudine in the various concentrations, m from (293.15 to 318.15) K and at 0.1 MPa pressure. The measured density and speed of sound data were used to calculate the apparent molar volume (V ϕ) and the isentropic compress...

A novel class of aqueous biphasic systems (ABS) formed by zwitterions (ZI) has been investigated in the present work. A series of water soluble ZIs have been synthesized using triethylamine, N -Methylimidazole, N -Vinylimidazole, pyridine, N -Methylpyrrolidine, N -Ethylpiperidine and 1,4 butane sultone. The synthesized ZIs were explored for their a...

In this study, we explored the catalyst‐free one‐pot multi‐component synthesis of 1,4‐dihydropyridine derivatives by following green chemistry protocol. The present approach shows the significant outcomes such as yield up to 94%, catalyst‐free reaction, easy workup procedure and shorter period of reaction time. In this work we also highlighted the...

The hydrophobic ionic liquid containing non-fluorinated anion and suitable diluents are two main requirements for the eco-friendly extraction of metal ions from aqueous phase. The information about volumetric properties of their binary solution shed light on the molecular interactions that govern extraction mechanism. In this manuscript, we report...

Thermophysical properties of halogen-free ionic liquids are gaining significant attention for industrial applications. In this context, trioctylalkylammonium bis(salicylato)borate (N888n-BScB) ionic liquids having variable alkyl chain length (n = 4, 8, 12, 16) are synthesized to explore the effect of chain length and temperature on their physicoche...