Richa Rajak
@iiti.ac.in
PhD Scholar
IIT Indore
RESEARCH INTERESTS
Inorganic Chemistry
Scopus Publications
- Exploring Hydrogen-Bonded 3D MOFs: High-Performance, Thermally Stable Self-Assembled Iodine-Encapsulated Frameworks with Optimal Energetic Potential
Manojkumar Jujam, Richa Rajak, Navaneet Kumar, Vikas D. Ghule, Srinivas Dharavath
Chemistry A European Journal, 2025
Modern high‐performing insensitive energetic materials are becoming more and more in demand to meet the growing needs of civilians and military applications. Here, the self‐assembly of azole‐based energetic molecules was described to construct potassium‐ and sodium‐based energetic metal‐organic frameworks (E‐MOFs) using polyazole‐based energetic 5,5′‐(2‐((1H‐tetrazol‐5‐yl)methyl)‐2H‐1,2,3‐triazole‐4,5‐diyl)bis(1H‐tetrazole) (TBTT) linker. The X‐ray analysis authenticates K‐MOF (1) and Na‐MOF (2), introducing hydrogen‐bonded 3D frameworks. Both compounds were extensively studied by thermogravimetric analysis‐differential scanning calorimetry (TGA‐DSC), elemental analysis (EA), infrared spectroscopy (IR), Scanning Electron Microscopy (SEM), dynamic light scattering (DLS), and powder X‐ray diffraction analyses (PXRD). Further, mechanical sensitivity, detonation properties, and Hirshfeld surface analyses were examined. As expected, both E‐MOFs showed excellent thermal decomposition temperature (Td = 333–387 °C), which exceeds benchmark explosives like hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) (210 °C), 2,4,6‐trinitrotoluene (TNT), hexanitrostilbene (HNS) (318 °C), and 2,4,6‐triamino‐1,3,5‐trinitrobenzene (TATB) (315 °C). They also have shown high positive heat of formation (HOF = 366–525 kJ/mol) and superior detonation performance (VOD = 6857–8903 m/s; DP = 17.41–28.23 GPa). Additionally, the two E‐MOFs exhibited low sensitivity toward impact sensitivity (IS > 60 J) and friction sensitivity (FS > 360 N), which may be attributed to strong structural reinforcement and multiple hydrogen bonding interactions, which is also proven by Hirshfeld surface analyses. Moreover, the high covalent bonds are beneficial in strengthening the E‐MOF structures, which require high energy to collapse, thereby sustaining excellent thermal stability. E‐MOFs 1 and 2 exhibit high iodine encapsulation and recyclability, maintaining effectiveness over six cycles, making them ideal for water remediation. Thus, compounds 1 and 2 can serve as promising next‐generation highly thermally stable energetic materials, which can be a perfect replacement for currently used conventional explosives RDX, HNS, and TATB. - Exploring Green Pyrotechnic Formulations and Primary Explosives with 1,3,4-Oxadiazole-Based Micro and Submicron Energetic Coordination Polymers
Shreyasi Banik, Richa Rajak, Jean'ne M. Shreeve, Srinivas Dharavath
Small, 2025
Alkali and alkaline‐earth metal incorporated 5,5′‐dinitramino‐3,3′‐azo‐1,3,4‐oxadiazole (H2DNAO) based Energetic Coordination Polymers (ECPs), namely dipotassium 5,5′‐dinitramino‐3,3′‐azo‐1,3,4‐oxadiazole(K2DNAO), dicesium 5,5′‐dinitramino‐3,3′‐azo‐1,3,4‐oxadiazole(Cs2DNAO) and barium 5,5′‐dinitramino‐3,3′‐azo‐1,3,4‐oxadiazole(BaDNAO) are synthesized for the first time. Synthesized ECPs are thoroughly characterized using infrared spectroscopy (IR), elemental analysis (EA), thermogravimetric analysis and differential scanning calorimetry (TGA‐DSC), field emission scanning electron microscopy (FE‐SEM), and dynamic light scattering (DLS), UV–vis spectroscopy. All ECPs are also confirmed by single‐crystal X‐ray diffraction technique (SC‐XRD). The micro‐ECPs exhibit excellent densities (1.98–2.80 g cm−3), insensitivities (IS: 25‐40 J; FS: 240‐360 N), and good thermal stabilities (Td: 182–212 °C). K2DNAO and Cs2DNAO show good detonation performance (VOD:7460‐7893 m s−1; DP: 27.5‐30.6 GPa), respectively. To further investigate sub‐micron‐energetics, three sub‐micron ECPs are prepared from their micro counterparts using ultrasonication method, demonstrating significant improvement in thermal stability (Td: 194–221 °C) but are highly sensitivity (IS: 2‐15J; FS: 40‐360N). Burning tests of two experimental formulations using micro K2DNAO and Cs2DNAO demonstrate their potential in green pyrotechnic applications. Interestingly, the submicron‐counterparts show remarkable initiating capability. Considering their ease of synthesis, and safety profile, these materials can be effectively transported in their microform and can be rapidly converted into submicron‐form on demand, making them suitable for pyrotechnic applications. - Trailblazing 3D MOFs Featuring 1,2,4-Dinitrimino Triazole: Redefining Energetic Materials and Iodine Encapsulation
Manojkumar Jujam, Richa Rajak, Srinivas Dharavath
Advanced Functional Materials, 2025
The quest for high‐performance energetic materials for defense and aerospace has intensified, focusing on balancing energy output and safety. This study presents the synthesis of 3D energetic metal‐organic frameworks (EMOFs) [Na3(DNT)(H2O)]n (Na‐MOF), [K2(DNT)2(H2O)]n (K‐MOF), and [Cs2(DNT)]n (Cs‐MOF) using 1,2,4‐dinitrimino triazole (DNT) through a hydrothermal process. The synthesized EMOFs are characterized using infrared spectroscopy, powder X‐ray diffraction, scanning electron microscopy (SEM), elemental analysis, and thermogravimetric analysis and differential scanning calorimetry, and structures confirmed via single‐crystal X‐ray diffraction, revealing 3D frameworks with crystal densities of 2.15, 2.16, and 2.86 g cm−3, respectively. Among them, Na‐MOF exhibits excellent detonation performance (VOD = 8900 m s−1, DP = 26.21 GPa), high thermal stability (Td = 369 °C), and insensitivity to impact and friction (IS = 40 J, FS = 360 N). K‐MOF displays balanced energetic and mechanical properties, while Cs‐MOF, though moderate in energetic performance, shows significant potential in pyrotechnic applications, producing a bright red flame. Intermolecular interactions are analyzed through Hirshfeld surface, 2D fingerprint, and SEM analyses, enhancing the understanding of particle size and morphology. Na‐MOF also demonstrates high iodine encapsulation capacity, positioning it as a potential replacement for traditional materials like RDX and heat‐resistant explosives such as HNS, with comparability to PYX. - Elevating the energetic capabilities of metal coordination compounds by incorporating nitrate anions
Abhishek Kumar Yadav, Richa Rajak, Srinivas Dharavath
Dalton Transactions, 2024
In the realm of energetic materials research, there has been notable interest in energetic coordination compounds (ECCs) owing to their remarkable thermal stability and resistance to mechanical stimuli. - Mixed-Metallic Energetic Metal-Organic Framework: New Structure Motif for Potential Heat-Resistant Energetic Materials
Richa Rajak, Parasar Kumar, Srinivas Dharavath
Crystal Growth and Design, 2024
The incessant pursuit of heat-resistant explosives with balanced energetic performance and safety is indispensable in civil and military sectors, particularly when employed in harsh environments. Herein, a new nanostructured highly energetic metal–organic framework (E-MOF), based on nickel(II) and sodium(I) mixed-metal has been constructed using an energetic poly tetrazole molecule by the hydrothermal approach. The Na/Ni-MOF was thoroughly characterized using infrared radiation (IR), thermogravimetric analysis and differential scanning calorimetry, scanning electron microscopy, and powder X-ray diffraction analyses. Further, the crystal structure was authenticated by single crystal X-ray diffraction analysis, and their crystal packing features were well explored, revealing a wave-like 3D framework having a crystal density of 1.985 g cm –3 . This mixed-metallic E-MOF demonstrated a good enthalpy of combustion (−7.91 kJ·g –1 ), a good velocity of detonation (VOD = 7410 m s –1 ) exceeding that of trinitrotoluene (TNT, 6820 m/s) and Hexanitrostilbene (HNS, 7164 m/s), and excellent insensitivity [impact sensitivity (IS) > 40 J and friction sensitivity (FS) > 360 N]. Additionally, it exhibits outstanding thermal stability ( T d = 387 °C). These fine-tuned properties are superior to those of continuously used benchmark heat-resistant explosives HNS and 2,4,6-triamino-1,3,5-trinitrobenzene, suggesting that the newly reported poly tetrazole-based E-MOF is beneficial for improved physical performance. The results given in the present work highlighted the advantages of the mixed-metallic E-MOF as a potential heat-resistant explosive for future applications. - Highly Dense N-N-Bridged Dinitramino Bistriazole-Based 3D Metal-Organic Frameworks with Balanced Outstanding Energetic Performance
Richa Rajak, Navaneet Kumar, Vikas D. Ghule, Srinivas Dharavath
ACS Applied Materials and Interfaces, 2024
Due to the inherent conflict between energy and safety, the construction of energetic materials or energetic metal-organic frameworks (E-MOFs) with balanced thermal stability, sensitivity, and high detonation performance is challenging for chemists worldwide. In this regard, in recent times self-assembly of energetic ligands (high nitrogen- and oxygen-containing small molecules) with alkali metals were probed as a promising strategy to build high-energy materials with excellent density, insensitivity, stability, and detonation performance. Herein, based on the nitrogen-rich N,N'-([4,4'-bi(1,2,4-triazole)]-3,3'-dial)dinitramide (H2BDNBT) energetic ligand, two new environmentally benign E-MOFs including potassium [K2BDNBT]n (K-MOF) and sodium [Na2BDNBT]n (Na-MOF) have been introduced and characterized by NMR, IR, TGA-DSC, ICP-MS, PXRD, elemental analyses, and SCXRD. Interestingly, Na-MOF and K-MOF demonstrate solvent-free 3D dense frameworks having crystal densities of 2.16 and 2.14 g cm-3, respectively. Both the E-MOFs show high detonation velocity (VOD) of 8557-9724 m/s, detonation pressure (DP) of 30.41-36.97 GPa, positive heat of formation of 122.52-242.25 kJ mol-1, and insensitivity to mechanical stimuli such as impact and friction (IS = 30-40 J, FS > 360 N). Among them, Na-MOF has a detonation velocity (9724 m/s) superior to that of conventional explosives. Additionally, both the E-MOFs are highly heat-resistant, having higher decomposition (319 °C for K-MOF and 293 °C for Na-MOF) than the traditional explosives RDX (210 °C), HMX (279 °C), and CL-20 (221 °C). This stability is ascribed to the extensive structure and strong covalent interactions between BDNBT2- and K(I)/Na(I) ions. To the best of our knowledge, for the first time, we report dinitramino-based E-MOFs as highly stable secondary explosives, and Na-MOF may serve as a promising next-generation high-energy-density material for the replacement of presently used secondary thermally stable energetic materials such as RDX, HNS, HMX, and CL-20. - Energetic coordination compounds: self-assembled from the nitrogen-rich energetic C-C bonded pyrazoles and triazoles
Abhishek Kumar Yadav, Richa Rajak, Vikas D. Ghule, Srinivas Dharavath
Dalton Transactions, 2023
In energetic materials research, energetic coordination compounds (ECCs) have received much attention due to their high thermal stability and insensitivity to mechanical stimuli. - Poly Tetrazole Containing Thermally Stable and Insensitive Alkali Metal-Based 3D Energetic Metal-Organic Frameworks
Richa Rajak, Parasar Kumar, Vikas D. Ghule, Srinivas Dharavath
Inorganic Chemistry, 2023
Poly tetrazole-containing thermally stable and insensitive alkali metal-based 3D energetic metal-organic frameworks (EMOFs) are promising high energy density materials to balance the sensitivity, stability, and detonation performance of explosives in defense, space, and civilian applications. Herein, the self-assembly of L3- ligand with alkali metals Na(I) and K(I) was prepared at ambient conditions, introducing two new EMOFs, [Na3(L)3(H2O)6]n (1) and [K3(L)3(H2O)3]n (2). Single crystal analysis reveals that Na-MOF (1) exhibited a 3D wave-like supramolecular structure with significant hydrogen bonding among the layers, while K-MOF (2) also featured a 3D framework. Both EMOFs were thoroughly characterized by NMR, IR, PXRD, and TGA/DSC analyses. Compounds 1 and 2 show excellent thermal decomposition Td = 344 and 337 °C, respectively, compared to the presently used benchmark explosives RDX (210 °C), HMX (279 °C), and HNS (318 °C), which is attributed to structural reinforcement induced by extensive coordination. They also show remarkable detonation performance (VOD = 8500 m s-1, 7320 m s-1, DP = 26.74 GPa, 20 GPa for 1 and 2, respectively) and insensitivity toward impact and friction (IS ≥ 40 J, FS ≥ 360 N for 1; IS ≥ 40 J, FS ≥ 360 N for 2). Their excellent synthetic feasibility and energetic performance suggest that they are the perfect blend for the replacement of present benchmark explosives such as HNS, RDX, and HMX. - Effect of Electrolytic Cations on a 3D Cd-MOF for Supercapacitive Electrodes
Rakesh Deka, Richa Rajak, Viresh Kumar, Shaikh M. Mobin
Inorganic Chemistry, 2023
A cadmium-based metal-organic framework (Cd-MOF) is synthesized in a facile manner at ambient temperature by an easy slow diffusion process. The three-dimensional (3D) structure of Cd-MOF is authenticated by single-crystal X-ray diffraction studies and exhibits a cuboid-shaped morphology with an average edge length of ∼1.13 μm. The prepared Cd-MOF was found to be electroactive in nature, which resulted in a specific capacitance of 647 F g-1 at 4 A g-1 by maintaining a retention of ∼78% over 10,000 successive cycles in the absence of any binder. Further, to distinguish the efficiency of Cd-MOF electrodes, different electrolytes (NaOH, KOH, and LiOH) were explored, wherein NaOH revealed a higher capacitive response due to its combined effect of ionic and hydrated ionic radii. To investigate the practical applicability, an asymmetric supercapacitor (ASC) device is fabricated by employing Cd-MOF as the positive electrode and activated carbon (AC) as the negative electrode, enabling it to light a commercial light-emitting diode (LED) bulb (∼1.8 V). The as-fabricated ASC device delivers comparable energy density and power density. - Two-dimensional layered nickel-based coordination polymer for supercapacitive performance
Rakesh Deka, Viresh Kumar, Richa Rajak, Shaikh M. Mobin
Sustainable Energy and Fuels, 2022
A nickel based coordination polymer (Ni-CP) is synthesized by slow diffusion technique which reveals a 2D layer like structure having sql topology, further this Ni-CP was employed for high performance supercapacitor application. - Construction of a Cu-Based Metal-Organic Framework by Employing a Mixed-Ligand Strategy and Its Facile Conversion into Nanofibrous CuO for Electrochemical Energy Storage Applications
Richa Rajak, Mohit Saraf, Praveen Kumar, Kaushik Natarajan, Shaikh M. Mobin
Inorganic Chemistry, 2021 - Recent highlights and future prospects on mixed-metal MOFs as emerging supercapacitor candidates
Richa Rajak, Ravinder Kumar, Shagufi Naz Ansari, Mohit Saraf, Shaikh M. Mobin
Dalton Transactions, 2020 - Mixed-Ligand Architected Unique Topological Heterometallic Sodium/Cobalt-Based Metal-Organic Framework for High-Performance Supercapacitors
Richa Rajak, Mohit Saraf, Shaikh M. Mobin
Inorganic Chemistry, 2020 - Dy(III)-Based Metal-Organic Framework as a Fluorescent Probe for Highly Selective Detection of Picric Acid in Aqueous Medium
Richa Rajak, Mohit Saraf, Sanjay K. Verma, Ravinder Kumar, Shaikh M. Mobin
Inorganic Chemistry, 2019 - Electrochemical energy storage properties of solvothermally driven ZnFe2O4 microspheres
Mohit Saraf, Kaushik Natarajan, Anoop K Gupta, Pawan Kumar, Richa Rajak, Shaikh M Mobin
Materials Research Express, 2019 - MOF Derived High Surface Area Enabled Porous Co3O4 Nanoparticles for Supercapacitors
Mohit Saraf, Richa Rajak, Shaikh M. Mobin
Chemistryselect, 2019 - Catalytic Application of Tactically Aligned Cd(II)-Based Luminescent 3D-Supramolecular Networks
Richa Rajak, Akbar Mohammad, Prakash Chandra, Shaikh M. Mobin
Chemistryselect, 2019 - Remediation of water contaminants
Akbar Mohammad, Khursheed Ahmad, Richa Rajak, Shaikh M. Mobin
Handbook of Ecomaterials, 2019 - Robust heterostructures of a bimetallic sodium-zinc metal-organic framework and reduced graphene oxide for high-performance supercapacitors
Richa Rajak, Mohit Saraf, Shaikh M. Mobin
Journal of Materials Chemistry A, 2019 - Enthralling Adsorption of Different Dye and Metal Contaminants from Aqueous Systems by Cobalt/Cobalt Oxide Nanocomposites Derived from Single-Source Molecular Precursors
Akbar Mohammad, Shagufi Naz Ansari, Archana Chaudhary, Khursheed Ahmad, Richa Rajak, Mohd. Tauqeer, Shaikh M. Mobin
Chemistryselect, 2018 - Binder Free Modification of Glassy Carbon Electrode by Employing Reduced Graphene Oxide/ZnO Composite for Voltammetric Determination of Certain Nitroaromatics
Akbar Mohammad, Khursheed Ahmad, Richa Rajak, Shaikh M. Mobin
Electroanalysis, 2018 - Design and construction of a ferrocene based inclined polycatenated Co-MOF for supercapacitor and dye adsorption applications
Richa Rajak, Mohit Saraf, Akbar Mohammad, Shaikh M. Mobin
Journal of Materials Chemistry A, 2017 - Construction of TiO2 nanosheets modified glassy carbon electrode (GCE/TiO2) for the detection of hydrazine
Khursheed Ahmad, Akbar Mohammad, Richa Rajak, Shaikh M Mobin
Materials Research Express, 2016 - A fascinating multitasking Cu-MOF/rGO hybrid for high performance supercapacitors and highly sensitive and selective electrochemical nitrite sensors
Mohit Saraf, Richa Rajak, Shaikh M. Mobin
Journal of Materials Chemistry A, 2016 - Synthesis and characterization of polyhedral-based metal-organic frameworks using a flexible bipyrazole ligand: Topological analysis and sorption property studies
Kapil Tomar, Richa Rajak, Suresh Sanda, Sanjit Konar
Crystal Growth and Design, 2015
