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An efficient and environmentally benign synthesis of a new class of acridinedione embedded spirooxindolo/acenaphthenothiopyrrolizidines and spirooxindolo/acenathenoindolizidines has been synthesized in good to excellent yields employing ionic liquid accelerated one-pot [3 + 2]-cycloaddition strategy. The pre-requisite starting substrates, O-acryloyl acridinediones were prepared from dimedone in three good yielding steps, while the 1,3-dipole was derived in situ from isatin/acenaphthenequinone and thiazolidine-4-carboxylc acid/l-pipecolinic acid via decarboxylative condensation. The cycloadduct possesses three stereogenic carbons, one of which is a spiro carbon through the formation of two C–C and one C–N bonds in one-pot synthetic transformation. Geometrical parameters of the synthesized compounds were calculated using the B3LYP/6-311g(d,p) level of theory. The activity of these molecules was evaluated against main protease of COVID-19 to screen them for their inhibitor efficiency. In order to get a broad understanding of the interactions of these synthesized ligands, a detailed molecular docking analysis was performed. Molecular docking analysis shows that compound 8b has the highest binding affinity toward the protein. The compound can be a potential candidate for the treatment of COVID-19.

The development of density functional theory (DFT) has significantly enhanced the use of computational chemistry as a tool in the design and development of ligands for the separation of actinides (An) and lanthanides (Ln) in the nuclear waste management. In the past, identifying new ligands involved either making incremental structural changes to existing ligands or conducting extensive laboratory testing of numerous compounds. However, these experimental methods are often costly and time-consuming. With the advancements in hardware and software, theoretical and computational chemistry has become a powerful and cost-effective approach in nuclear waste management research. The density functional theory (DFT), in particular, has played a pivotal role by enabling scientists to accurately predict the effectiveness of ligands based on electronic and molecular properties, as well as reactivity indices. This computational approach provides valuable insights into the separation efficiencies of ligands without the need for extensive experimental efforts. This review highlights the role of computational chemistry in the design of ligands for the separation of lanthanides and actinides in spent nuclear fuel processing. It discusses various design strategies and computational analyses used in ligand optimization, highlighting the potential applications of computational tools in guiding ligand design and improving separation processes. The work emphasizes the synergy between computational insights and experimental observations in lanthanide/actinide chemistry, which enhances understanding of complex phenomena and aids in the interpretation of experimental results. It also explores different design approaches that allow for fine-tuning of ligand properties and selectivity toward specific metal ions, ultimately improving separation efficiency. In this review, we will discuss some widely used computational tools in chemistry without delving into complex mathematical formulas. This will be particularly helpful for researchers who come from an experimental background and may not be as familiar with advanced mathematical concepts. The tools covered are bond order analysis, population analysis, quantum theory of atoms in molecules (QTAIM) analysis, Energy Decomposition Analysis (EDA), and thermodynamic analysis. These methods are explored in a more accessible manner for non-theoretical researchers. They provide valuable insights into bonding, binding, stability, non-bonding interactions, coordinating abilities and selectivity of organic ligands in extraction of actinides and lanthanides, thus providing useful information in the designing of ligands to enhance separation strategies. This review serves as an excellent resource for future ligand design, offering valuable insights into computational techniques used to understand the coordination and complexation behaviors of ligands. Also an attempt has been made to understand the role of DFT functionals in the calculations. It provides a foundation for researchers to comprehend and apply computational tools effectively in their investigations. [ABSTRACT FROM AUTHOR]

Organic fluorescence sensor for selectively detecting and quantifying toxic heavy metal ions has received significant interest due to their environmental hazards. Herein, we have designed and synthesized a simple tripodal Schiff base ligand (1) based on hydroxy-naphthaldehyde and tris(2-aminoethyl)amine (TREN) and demonstrated highly selective turn-on fluorescence sensing of Cd2+ ions. The free ligand did not show any fluorescence in DMF. In contrast, Cd2+ (10− 4 M) addition exhibited a strong enhancement of fluorescence at 450 nm. Interestingly, other metal ions including Zn2+, which exhibit similar chemistry, did not show any turn-on fluorescence. The concentration-dependent studies of 1 with Cd2+ showed the detection limit of 6.78 × 10− 8 M. NMR spectra of 1 with Cd2+ and computational studies were performed to understand the mechanism of sense. [ABSTRACT FROM AUTHOR]

Fluorescent proteins are currently the most extensively studied fluorescent markers used in bio-imaging, and many such fluorescent markers are used in research to label amino acids and proteins. However, developing suitable fluorescent probes to label peptides and proteins remains a major challenge. In this context, the twelve recently reported amino acid-coupled benzanthrone 2-aminoacetamide molecules (BA1–BA12) attracted our attention and we screened their intense luminescence properties computationally for bio-visualization applications. DFT calculations in the gas and solvent phases indicated the presence of N–H⋯O hydrogen bond interactions that stabilize the BA3, BA5, BA9, BA4, BA7 and BA12 molecules in the ground state. Electronic spectral studies reveal that these molecules have high Stokes shifts, which implies that they are excellent for bio-visualization applications. The sensing properties of these molecules are evaluated through molecular docking and 100 ns molecular dynamics simulations. These molecules are stabilized in the binding pockets of insulin amyloid fibrils and can easily dissociate from these fibrils after 50 ns. We believe that this research will be valuable in assisting researchers to design more efficient molecules for bio-imaging applications, addressing the ongoing need for suitable fluorescent probes for the labelling of peptides and proteins. [ABSTRACT FROM AUTHOR]

Partitioning of trivalent actinides (An(III)) from lanthanides (Ln(III)) during Spent Nuclear Fuel (SNF) reprocessing presents a major challenge due to the exhibition of very similar chemical properties. Although an array of phenanthroline-based ligands have surfaced to solve this problem, the recently reported soft – hard-donor-combined N, N'-diethyl-N.N'-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen) ligand has gained much attention. In this work, Et-Tol-DAPhen has been electronically modified with di and mono substitutions of phenol at the 4th and 5th positions. The structural properties and extraction abilities of these modified ligands have been studied using DFT calculations. The results reveal that the ligand (ETDP3) with diphenol substitutions at the 4th position has an excellent extraction capability with high selectivity toward Am(III) over Eu(III) ion. Electronic structure and bonding analyses provide insights into the nature of metal-ligand bonds in the ten coordinated ML(NO3)3 complexes [M = Am and Eu] and convey that in all the complexes the M-O bonds are stronger than the M-N bonds. The quantum theory of atoms in molecules (QTAIM) reveals the weak C-H – O interactions in these ML(NO3)3 complexes. The charge analysis explains the exceptional complexation behavior by determining the donor–acceptor interactions in the Am complexes. ΔΔG values obtained from thermodynamic analysis indicate the preferential selectivity of these ligands toward trivalent Am over Eu ions. Around 22% increased covalency is observed between M(NO3)3 and L in the Am complexes compared to that of the Eu complexes. Overall, this computational study offers an understanding of how beneficial it is to have mono- and diphenol substitutions at the fourth and fifth position of the phenanthroline-based ligands for effective actinide/lanthanide separation. [ABSTRACT FROM AUTHOR]

Designing organic ligands is a popular strategy in removing hazardous radioactive substances from nuclear wastewater which has been a major environmental concern. In this regard, a new family of alicyclic substituted 1, 10‐ phenanthroline‐2, 9‐diamide ligands has been reported recently for efficient extraction of Am3+ over Eu3+ ions. Thus, a series of 1, 10‐ phenanthroline‐2, 9‐diamide ligands with heterocyclic substituents (Pyrrolidine, Piperidine, Pyrrole and Dihydropyridine) and their 1 : 1 complexes (ML(NO3)3) have been considered for this investigation to understand the role of substitution of heterocycles in selective extraction process in nuclear waste management. An attempt has been made to unveil the complexation behaviour of these ligands with Am3+ and Eu3+ ions from DFT calculations. Electronic structure, Mulliken Population Analysis, Bond Order Analysis, QTAIM (Quantum Theory of Atoms in Molecules) Analysis, and EDA (Energy Decomposition Analysis) were all performed. We addressed the feasibility of ML(NO3)3 complex formation from thermodynamics perspective where Pyrrolidine moiety has been found to show highest selectivity for Am3+ ion. M−O bonds contribute more to the coordinating ability of the ligands than M−N bonds in each complex, according to the findings. Orbital interactions hold the key between M(NO3)3 and the ligand in stabilizing the complexes. The weak covalent character of Metal‐Ligand bonds is addressed from QTAIM analysis. In short, this study offers guidelines to use heterocycles efficiently to design better ligands for selective partitioning of trivalent Am over Eu ions in the spent nuclear fuel processing. [ABSTRACT FROM AUTHOR]