The crucial role of stability of intercalating agent for DNA binding studies in DMSO/water system.

In recent years, extensive research has been directed towards understanding the interactions between various zinc complexes with DNA, specifically delving into their intercalation and binding behaviors. The binding of zinc complexes to DNA is particularly intriguing due to their distinctive intercalating capabilities. This study unveils a remarkable phenomenon observed with a specific Zn complex, ([B-Zn-N3], where B is a Schiff base ligand), during DNA intercalation investigations in the popular DMSO-Water binary solvent mixture. An unanticipated observation revealed time-dependent changes in the UV-visible absorption spectroscopic studies, coupled with the existence of an isosbestic point. This observation questions the stability of the intercalating agent itself during the intercalation process. The emergence of a decomposed product during the intercalation study has been confirmed through various analytical techniques, including CHN analysis, MALDI mass, XPS, Raman spectroscopy, and Powder XRD. The change in the chemical species on intercalation is further substantiated by theoretical studies, adding depth to our understanding of the intricate dynamics at play during DNA intercalation with the [B-Zn-N3] complex in the DMSO-Water system.

Exploring the Gamma-Ray Enhanced NIR-Luminescence and Cytotoxic Potential of Lanthanide-Naphthalene Dicarboxylate based Metal-Organic Frameworks.

In this investigation, we explore the integration of lanthanides into Metal-Organic Frameworks (MOFs) to enable Near-Infrared (NIR) emission. Specifically, we focus on Lanthanide-Naphthalene Dicarboxylate based MOFs (Ln-MOFs), incorporating elements such as Praseodymium (Pr), Samarium (Sm), Dysprosium (Dy), and Erbium (Er). The synthesis of Ln-MOFs is achieved via the hydrothermal method. The structure, morphology, thermal stability, and luminescence properties of synthesized Ln-MOFs have been evaluated through different characterization techniques. Upon photoexcitation at 350 nm, Ln-MOFs show the emission in the Visible and NIR region. Further, the luminescence intensity of Ln-MOFs enhanced by 2-3 folds in the visible region and 6-8 folds in NIR region after exposing to Gamma irradiation at 150 kGy. Cytotoxic effect on the viability of MDA-MB 231 and MDA-MB 468 Triple negative breast cancer (TNBC) cells was evaluated by MTT assay. The results revealed that among all synthesized MOFs, Pr-MOF exhibited an aggressive cytotoxic effect. Additionally, analysis of phase-contrast microscopy data indicates that Pr-MOF induces alterations in the morphology of both MDA-MB 231 and MDA-MB 468 TNBC cells when compared to untreated controls. The findings in this study reveal the utilization of Ln-MOFs for studying cytotoxicity and highlight their ability to enhance near-infrared (NIR) emission when exposed to gamma radiation.

Unusual Effect of Minor Change in Ligand Substitution in Modulation of NIR Emission: A Case Study with [L-ZnII-LnIII] Complexes.

There have been numerous instances of lanthanide NIR emitting material where one or more types of ligands or metal ion-ligand complexes operate as antennas. The antenna's role in NIR emission has also been thoroughly investigated and validated. The emission properties of the different antennae are predicted to differ. Here we describe the structural and photophysical properties of two series of [ZnII-LnIII] complexes, where a minor difference between the two series (ethoxy vs methoxy substitution) affected the photophysical properties, particularly the f-f transition, in an unprecedented manner. Both steady-state and time-resolved luminescence spectra were affected by this change. Detailed single-crystal X-ray diffraction (SCXRD) and X-ray photoelectron spectroscopy (XPS) studies of both complexes revealed the crucial structural differences in crystal packing, which astonishingly remains unaffected in solution.

Biocompatible thermoresponsive N-isopropyl-N-(3-(isopropylamino)-3-oxopropyl)acrylamide-based random copolymer: synthesis and studies of its composition dependent properties and anticancer drug delivery efficiency.

A new acrylamide monomer, N-isopropyl-N-(3-(isopropylamino)-3-oxopropyl)acrylamide (M3i), consisting of both isopropyl and isopropylamidopropyl moieties, has been synthesized from isopropylamine and N-isopropylacrylamide via an aza-Michael addition reaction followed by amidation with acryloyl chloride. The homopolymer of M3i (polyM3i) and a series of random copolymers of M3i and poly(ethylene glycol)methyl ether acrylate (PEGA: CH2CHCO2(CH2CH2O)nMe, Mn = 480, n = 9 on average) with varying compositions have been synthesized via reversible addition-fragmentation chain transfer polymerization using 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) as well as 1-phenylethyl phenyl dithioacetate (PEPD) as a RAFT agent. These polymers have been characterized by 1H NMR, FTIR, GPC, UV-Vis, fluorescence, TGDTA, DSC, DLS, and TEM techniques. A lower critical solution temperature (LCST) and glass transition temperature (Tg) for polyM3i prepared using DDMAT were observed at 17 and 133 °C, respectively, while for a polymer formed using PEPD, no LCST was observed until 0 °C and its observed Tg was found at 127.3 °C. The polymers are thermally stable up to 300 °C. Upon an increase in the M3i content in the copolymers, LCST decreases, Tg increases, and the apparent hydrodynamic diameter decreases. Moreover, the effects of concentration and the addition of urea and sodium chloride on the LCST of the copolymer with an LCST close to body temperature were studied. Owing to the incorporation of PEGA, a higher critical micellar concentration and larger TEM particle size of this copolymer were observed with respect to those of polyM3i. The usefulness of the micelles of the copolymers as nano-carriers for the drug doxorubicin was explored. The in vitro tumoricidal activity of the micelles of the doxorubicin-loaded copolymers was also assessed against Dalton's lymphoma cells.

Anharmonic phonon interactions and the Kondo effect in a FeSe/Sb2Te3/FeSe heterostructure: a proximity effect between ferromagnetic chalcogenide and di-chalcogenide.

In this report, we have introduced magnetic ordering into the nontrivial system of conventional topological insulators (TIs) by creating magnetic interfaces. In this context, antimony di-chalcogenide Sb2Te3 sandwiched between two thin layers of FeSe was prepared using the pulsed laser deposition (PLD) technique. The prepared heterostructure demonstrated good crystallinity along with homogeneous morphology displaying pyramid-shaped characteristic triangular islands. To comprehend the temperature and magnetic field modulated inter-layer properties of the prepared hetero-structure, transport, magneto-transport and magnetic properties were investigated. These properties establish the signature of the Kondo effect below 15 K, which has been attributed to the antiferromagnetic spin alignment in that temperature range. At around 150 K, longitudinal and transverse resistivity shows the metal-semiconductor transition, which was further elucidated through the anharmonic decay model in vibration phonon modes using Raman spectroscopy. Furthermore, a significant local spin evolution was explored at around 475 K by studying the magnetic properties of the system. The temperature dependency of the Raman modes confirmed the spin-phonon coupling initiated by local charge ordering at the proximity of the interface in the prepared hetero-structure.

Confocal Raman microscopic evidence for cyclic water Pentamer, at high temperatures in a supramolecular host of [Cu(cyclam)(N3)2]·4H2O.

Here, we report the existence of a pentameric water cluster in the host framework of [Cu(cyclam)(N3)2]·4H2O, that is stable upto 167 °C, well above the boiling point of water. The pentameric cluster structure embedded in the host framework is evident from the single crystal studies. The high thermal stability is confirmed by TGA and temperature dependent confocal Raman microscopic studies, where loss of water bands is well captured between 167 and 170 °C, besides its existence through SCXRD studies. To the best of our knowledge, this is the first report where temperature dependent confocal Raman microscopic investigation is used to study the stability of water in crystal environment. The study promises that temperature dependent confocal Raman microscopy can be an efficient tool to investigate the existence and stability of small water clusters, precisely in restricted environments.

Synthesis, biological evaluation, Structure - Activity relationship studies of quinoline-imidazole derivatives as potent antimalarial agents.

In our efforts to identify novel chemical scaffolds for the development of antimalarial agents, a series of quinoline - imidazole hybrid compounds were synthesized and their blood-stage antimalarial activity was evaluated in both drug-sensitive and -multi drug-resistant (MDR) P. falciparum strains. The new analogs possess sub-micromolar activities against Plasmodium falciparum. Among all synthesized derivatives, 11(xxxii) exhibited significant antimalarial efficacy in-vitro against both CQ-sensitive (IC50-0.14 µM) and MDR strain (IC50- 0.41 µM) with minimal cytotoxicity and high selectivity. Structure-activity relationships revealed that Br and OMe substitutions on quinoline ring improved the antimalarial activity and selectivity index. The role of stereochemistry in the inhibitory activity was assessed by enantiomeric separation of a racemic mixture of 11(xxxii). The enantiomer (-)-11(xxxii) had potent antimalarial activity over the other isomer, with IC50 of 0.10 µM.

Lack of Environmental Sensitivity of a Naturally Occurring Fluorescent Analog of Cholesterol.

Dehydroergosterol (DHE, Δ5,7,9(11),22-ergostatetraen-3ß-ol) is a naturally occurring fluorescent analog of cholesterol found in yeast. Since DHE has been shown to faithfully mimic cholesterol in a large number of biophysical, biochemical, and cell biological studies, it is widely used to explore cholesterol organization, dynamics and trafficking in model and biological membranes. In this work, we show that DHE, in spite of its localization at the membrane interface, does not exhibit red edge excitation shift (REES) in model membranes, irrespective of the membrane phase. These results are reinforced by semi-empirical quantum chemical calculations of dipole moment changes of DHE in ground and excited states, which show a very small change in the dipole moment of DHE upon excitation. We conclude that DHE fluorescence exhibits lack of environmental sensitivity, despite its usefulness in monitoring cholesterol organization, dynamics and traffic in model and biological membranes.

Defect induced ferromagnetic ordering and room temperature negative magnetoresistance in MoTeP.

The magneto-transport, magnetization and theoretical electronic-structure have been investigated on type-II Weyl semimetallic MoTeP. The ferromagnetic ordering is observed in the studied sample and it has been shown that the observed magnetic ordering is due to the defect states. It has also been demonstrated that the presence of ferromagnetic ordering in effect suppresses the magnetoresistance (MR) significantly. Interestingly, a change-over from positive to negative MR is observed at higher temperature which has been attributed to the dominance of spin scattering suppression.

Donor triggered aggregation induced dual emission, mechanochromism and sensing of nitroaromatics in aqueous solution.

The title paper describes the photophysics of a series of 2-benzylidenemalononitrile (RDC) derivatives, having donor- π - acceptor (D-π-A) architecture in solution, solid state and in hydrosol. Interestingly, it is observed that by tuning the electronic energy levels via changing donor strength, one can play with the emissive properties to the large extent; from non- fluorescent to fluorescent, to aggregation induced dual fluorescence, to aggregation induced enhanced emission (AIEE). The nature of aggregation is studied by Field Emission Scanning Electron Microscope (FESEM). This aggregation induced emission (AIE) in hydrosol is used to develop a thin layer chromatography (TLC) based simple, easy to use technique to identify the trinitrophenol in aqueous solution as well as can distinguish the three positional nitrophenol derivatives.

Synthesis, structural, thermal, photophysical and vibrational spectroscopic studies of potassium-polynitrile based 3D coordination polymer.

Among various interactions (such as H-bonding, π - π stacking interaction) which are responsible for the fascinating metallo-architectures, cation - π interaction has emerged as a significantly important force. Moreover, it has now been observed that this interaction is found to be presented ubiquitous across several fields of contemporary interest, such as chemistry, material science, and biology. In this work, we have focused on the design and synthesis of a pentacyano organic anion and potassium cation based 3D coordination polymer (5CNP). The single-crystal XRD structure revealed fascinating structural arrangements due to the existence of several intra and interionic interaction. To the best of our knowledge, such polycyano aromatic system based 3D coordination polymer is not reported. In addition to single crystal X-ray diffraction (SCXRD), we have employed confocal Raman microscopic techniques to understand the structural aspects, particularly the pentacyano functional groups which are Raman active. Considering the prospect of 5CNP as a material, thermal stability, and structyral properties have been studied, in addition to detailed photophysical aspects. The photophysical responses in solid and in solution have been studied by steady and time-resolved fluorescence spectroscopy. Interesting photophysical observation is noted when studied in a binary mixture of THF-toluene. Scanning electron microscopy (SEM) studies have also been done for comprehensive understanding. In the end, cytotoxicity studies have been undertaken to evaluate the toxicity of 5CNP in our cells.

Modulation of Weak Interactions in Structural Isomers: Positional Isomeric Effects on Crystal Packing and Physical Properties and Solid-State Thin-Film Fabrication.

Selective formation of positional isomers and accordingly tuning the physicochemical properties of small conjugated organic molecules through structural isomers is an effective crystal engineering for a fascinating successful delivery of thermally stable and photophysically exciting compounds. By small structural skeleton changes, the single crystal of the naphthalenemaleonitrile isomers is found to exhibit a drastic change in crystal packing array, which in turn is found to tune the thermal and physicochemical properties. The α-isomer (A) forms the "herringbone packing" (HP) due to peri-interaction-sensitive C-H···(Ar)π (Ar = naphthalene ring) interactions, and the ß-isomer (B) forms the "bricklayer packing" (BP) due to π(C≡N)···π(Ar) stacking interactions. These two positional isomers have revealed insight of molecular packing-dependent structure-property relationship. In this report, we show that a simple modification of relatively less common weak interactions, such as C-H···π(Ar) ↔ π(C≡N)···π(Ar), through the preparation of isomers, can lead to a drastic change in crystal packing (HP ↔ BP). Also, this report demonstrates that by a small structural diversity, one can obtain significant changes in the physicochemical properties like melting behavior, enthalpy, entropy, and electrical properties in the solid state. Therefore, it transpires from this study that structural isomer provides a useful complement to intermolecular nonbonding interactions as a tool to design new promising materials.

Towards the critical understanding of selected vibrational features in biologically important dicyano aromatic conjugated molecules: Importance of electron donating/withdrawal groups and geometry associated with dicyano group.

The Raman spectra of a series of synthesized DC molecules (benzylidene malononitrile derivatives) with different electron donating (EDG) and electron withdrawing (EWG) group have been presented and analyzed with DFT calculated spectra. In particular, different functional groups effect on cyano stretching (∼2200 cm-1), phenyl ring breathing and alkenic double bond stretch which often appears mixed up (1475-1650 cm-1) are studied systematically for several aromatic conjugated DC derivatives. Interestingly, symmetric stretching frequency of the DC compounds having two CN groups at geminal position appears at higher wavenumber (by 11-15 cm-1) compared to their corresponding asymmetric stretch frequency. Angle (between dicyano group) dependent theoretical study indicates that the relative appearance of cyano symmetric/anti-symmetric stretching frequency depends on whether dicyano groups are at the geminal or vicinal position and the angle between them. Complete band assignments of observed Raman frequencies have been performed by potential energy distributions (PEDs) available in GAR2PED software. Our results will help to understand the vibrational feature of this important class of compounds in biological medium when used as probe.

Evidence of CT complex formation between a probe and unreacted methylimidazole in imidazolium cation based ionic liquids: sensing by functionalised 2-benzyledinemalononitrile.

Here we report for the first time that unreacted N-methylimidazole (MIM) which is often a common impurity, can corrupt the results of a photophysical investigation of a probe molecule in imidazolium cation based RTILs. In addition, we propose a new type of sensor (functionalised 2-benzyledinemalononitrile derivative) for easy colorimetric detection and quantitative estimation of unreacted colourless MIM in RTILs.

Temperature sensor probe based on intramolecular charge transfer (ICT) & reversible solute-solvent interaction in solution.

In this present work, we have developed a temperature sensitive ICT probe (KNP) to investigate alternation of ICT process with the temperature in polar protic solvents. The H-bonding interaction is found to play a key role on solute-solvent interaction to become a temperature sensitive ICT probe in solution. From temperature dependent UV-Vis spectra, it is cleared that the solute-solvent interaction is reversible in nature with temperature and affected by concentration in polar protic solvents. The reversible solute-solvent interaction is observed by monitoring the intensity variation of intramolecular charge transfer (ICT) band with temperature in solution.

Evidence of C--F-P and aromatic π--F-P weak interactions in imidazolium ionic liquids and its consequences.

A simple change from alkyl group to alkene in side chain of imidazolium cation with same anion resulted in a drastic impact on physical properties (e.g., melting point) from bmimPF6 IL to cmimPF6 IL. The underlying reasons have been elucidated by structural and interaction studies with the help of DSC, SCXRD, vibrational and multi-nuclear NMR spectroscopic techniques. Experiments reveal existence of new weak interactions involving the carbon and π cloud of the imidazolium aromatic ring with fluoride of PF6 anion (i.e., C2--F-P and π--F-P) in cmimPF6 but are absent in structurally similar prototype IL, bmimPF6. Though weak, these interactions helped to form ladder type supramolecular arrangement, resulting in quite high melting point for cmimPF6 IL compared to bmimPF6 IL. These findings emphasize that an IL system can behave uniquely because of the existence of uncommon weak interactions.

Microheterogeneity in imidazolium and piperidinium cation-based ionic liquids: 1D and 2D NMR studies.

Existence of microheterogeneity of imidazolium and piperidinium cation-based ionic liquids (ILs) containing PF6 and NTf2 anions has been investigated by 1D and 2D NMR spectroscopy. 2D NMR (especially NOESY and HOESY) has been employed for studying the interactions present between cation and anion as well as the intermolecular interaction among cations. HOESY spectrum shows that fluorine of anion ( PF6- and NTf2-) significantly interacts with proton of the cations. Combined results of HOESY and NOESY for imidazolium IL indicate that the PF6- and imidazolium cation are distributed in organized manner, resulting a heterogeneous environment in liquid state. We have also observed existence of heterogeneous environment for piperidinium cation-based ILs which is different from imidazolium ILs. It appears that existence of microheterogeneity in IL is ubiquitous and therefore open up the ILs field to revisit. Copyright © 2017 John Wiley & Sons, Ltd.

Microscopic solvation environments in a prototype room-temperature ionic liquid as elucidated by resonance Raman spectroscopy of iodine and bromine.

Microscopic solvation environments in a prototype ionic liquid, bmimTf2N; 1-butyl-3-methyl-imidazolium-bis(trifluoromethanesulfonyl)imide, have been studied with the use of halides, X2 and Xn- (X=I, Br; n=3,5), as molecular probes. Resonance Raman spectroscopy has been used to detect these halogen species existing in bmimTf2N as well as in reference solvents including heptane, cyclohexane, KX/H2O and benzene. In heptane and cyclohexane, only free X2 species are detected. In KX/H2O, only Xn- and, in benzene, only benzene-X2 complexes are detected. On the contrary, free X2 and Xn- are concomitantly detected in bmimTf2N, indicating that there are two distinct solvation environments in bmimTf2N, non-polar environments that solvate free X2 and polar environments that stabilize Xn-. These two distinct solvation environments are most likely to arise from microscopic structural heterogeneity of ionic liquids.