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.

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.

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.

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.

Complementing Crystallography with Ultralow-Frequency Raman Spectroscopy: Structural Insights into Nitrile-Functionalized Ionic Liquids.

Functionalized ionic liquids are a subclass of ionic liquids that are tailored for a specific application. Structural characterization in both solid and liquid phases is central to understanding their physical properties. Here, we used ultralow-frequency Raman spectroscopy, which can measure Raman spectra down to approximately 5 cm(-1) , to study the structures and physical properties of 1-(4-cyanobenzyl)-3-methylimidazolium salts with five different anions. A comparison of the observed low-frequency Raman spectral patterns enabled us to predict the crystal symmetry of one of the synthesized salts for which single-crystal X-ray diffraction data were unobtainable. Real-time tracking of the low-frequency Raman spectral changes during melting revealed peak shifts indicative of different degrees of microscopic heterogeneity in the ionic liquids. The results show that our method provides a facile means that is complementary to X-ray crystallography, for obtaining structural information of ionic liquids.

Manipulating the proton transfer process in molecular complexes: synthesis and spectroscopic studies.

The proton transfer process in carefully designed molecular complexes has been investigated directly in the solid and solution phase. SCXRD studies have been employed to investigate the N-H-O bonding interaction sites of the molecular complexes, with additional experimental support from FTIR and Raman spectroscopic studies, to gain information on the relative position of hydrogen in between the N and O centers. Further, the proton transfer process in solution is studied using UV-Visible spectroscopy through monitoring the intramolecular charge transfer (ICT) process in these molecular complexes, which is primarily governed by the number of electron withdrawing groups (nitro groups) on proton donor moieties (NP, DNP and TNP). It is found that the magnitude of the ICT process depends on the extent of proton transfer, which on the other hand depends on the relative stabilities of the constituent species (phenolate species). A correlation is observed between an increase in the number of nitro groups and an increase in the melting point of the molecular complexes, indicating the enhancement of ionic character due to the proton transfer process. The aliphatic H-bonding is identified and monitored using (1)H-NMR spectroscopy, which reveals that the identity of molecular complexes in solution interestingly depends on the extent of proton transfer, in addition to the nature of the solvents. The aliphatic C-H-O H-bonding interaction between the oxygen atom of the nitro group and the alkyl hydrogen in piperidinium was also found to play a significant role in strengthening the primary interaction involving a hydrogen transfer process. The conductivity of the molecular complexes increases with an increase in the number of nitro groups, indicating the enhancement in ionic character of the molecular complexes.

Significance of weak interactions in imidazolium picrate ionic liquids: spectroscopic and theoretical studies for molecular level understanding.

The effects of interionic hydrogen bonding and π-π stacking interactions on the physical properties of a new series of picrate anion based ionic liquids (ILs) have been investigated experimentally and theoretically. The existence of aromatic (C2-HO) and aliphatic (C7-HO-N22 and C6-HO-N20) hydrogen bonding and π-π stacking interactions in these ILs has been observed using various spectroscopic techniques. The aromatic and aliphatic C-HO hydrogen bonding interactions are found to have a crucial role in binding the imidazolium cation and picrate anion together. However, the π-π stacking interactions between two successive layers are found to play a decisive role in tight packing in ILs leading to differences in physical properties. The drastic difference in the melting points of the methyl and propyl derivatives (mmimPic and pmimPic respectively) have been found to be primarily due to the difference in the strength and varieties of π-π stacking interactions. While in mmimPic, several different types of π-π stacking interactions between the aromatic rings (such as picrate-picrate, picrate-imidazole and imidazolium-imidazolium cation rings) are observed, only one type of π-π stacking interaction (picrate-picrate rings) is found to exist in the pmimPic IL. NMR spectroscopic studies reveal that the interaction of these ILs with solvent molecules is different and depends on the dielectric constant of the solvent. While an ion solvation model explains the solvation in high dielectric solvents, an ion-pair solvation model is found to be more appropriate for low dielectric constant solvents. The enhanced stability of these investigated picrate ILs compared with that of inorganic picrate salts under high doses of γ radiation clearly indicates the importance of weak interionic interactions in ILs, and also opens up the possibility of the application of picrate ILs as prospective diluents in nuclear separation for advanced fuel cycling process.

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.

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.

Synthesis and study of the properties of stereocontrolled poly(N-isopropylacrylamide) gel and its linear homopolymer prepared in the presence of a Y(OTf)3 Lewis acid: effect of the composition of methanol-water mixtures as synthesis media.

Poly(N-isopropylacrylamide) (PNIPAM) hydrogels and the corresponding linear homopolymers were synthesized in different methanol-water mixtures (x(m) = 0, 0.13, 0.21, 0.31, 0.43, 0.57, and 0.76, where x(m) is the mole fraction of methanol) in the presence of 0.1 M Y(OTf)(3) Lewis acid. The isotacticity (meso dyad (m), %) and cloud-point temperature of these homopolymers were gradually increased and decreased, respectively, with the increase in the x(m) values of the synthesis solvent mixtures. Moreover, the corresponding linear PNIPAM homopolymers prepared in the absence of Y(OTf)(3) showed an almost constant isotacticity of m = 45% and a cloud-point temperature of 33.0 °C. A SEM study revealed that the resulting hydrogels were highly porous except for the gels prepared at x(m) = 0 and 0.76. The swelling ratios of these hydrogels in water at different temperatures and in different methanol-water mixtures at 20 °C and the deswelling rate and the reswelling rate of these hydrogels were studied. All of these swelling results were compared with that of the corresponding gels prepared in the absence of a Lewis acid (Biswas, C. S.; Patel, V. K.; Vishwakarma, N. K.; Mishra, A. K.; Bhimireddi, R.; Rai, R.; Ray, B. J. Appl. Polym. Sci.2012, DOI: 10.1002/app.36318) and explained on the basis of the porosity of the gel, the state of aggregation and isotacticity of the PNIPAM chain segment, and the cononsolvency of the methanol-water mixture toward the PNIPAM chain segment.

Heteroleptic dipyrrinato complexes containing 5-ferrocenyldipyrromethene and dithiocarbamates as coligands: selective chromogenic and redox probes.

Six heteroleptic dipyrrinato complexes [Ni(fcdpm)(dedtc)] (1), [Ni(fcdpm)(dipdtc)] (2), [Ni(fcdpm)(dbdtc)] (3), [Pd(fcdpm)(dedtc)] (4), [Pd(fcdpm)(dipdtc)] (5), and [Pd(fcdpm)(dbdtc)] (6) (fcdpm = 5-ferrocenyldipyrromethene; dedtc = diethyldithiocarbamate; dipdtc = diisopropyldithiocarbamate; dbdtc = dibutyldithiocarbamate) have been synthesized and characterized by elemental analyses and spectral (ESI-MS, IR, (1)H, (13)C NMR, UV-vis) and electrochemical studies. Crystal structures of 1, 2, 4, and 5 have been authenticated by X-ray single-crystal analyses. Nickel-based complexes 1-3 display selective chromogenic and redox sensing for Hg(2+) and Pb(2+) ions, while palladium complexes 4-6 display selective chromogenic and redox sensing only for Hg(2+). Electronic absorption, ESI-MS, and electrochemical studies indicated that sensing arises from interaction between 1-3 and Hg(2+)/Pb(2+) through sulfur of the coordinated dithiocarbamates, while it arises from the pyrrolic nitrogen of fcdpm and dithiocarbamate sulfur from 4-6 and Hg(2+). Different modes of binding between Ni and Pd complexes have further been supported by theoretical studies. The receptor-cation binding constants (K(a)) and stoichiometry between probes and Hg(2+)/Pb(2+) have been estimated by the Benesi-Hildebrand method and Job's plot analysis. Detection limits for 1-3 toward Hg(2+)/Pb(2+) and 4-6 for Hg(2+) have been found to be reasonably high.

Inter- and intramolecular Mitsunobu reaction and metal complexation study: synthesis of S-amino acids derived chiral 1,2,3,4-tetrahydroquinoxaline, benzo-annulated [9]-N3 peraza, [12]-N4 peraza-macrocycles.

Substituted 1,2,3,4-tetrahydroquinoxaline, benzo-annulated unsymmetrical chiral [9]-N(3) peraza, and [12]-N(4) peraza-macrocycles have been synthesized employing an inter- and intramolecular Mitsunobu reaction from an amino acid derived common synthetic intermediate 3. The metal complexation study of these macrocycles has been investigated by UV-visible spectroscopic technique with binding constant (K(b)) value 1.84 × 10(3) dm(3) mol(-1) using the Benesi-Hildebrand equation and a Gibbs free energy (ΔG) -19.4 kJ mol(-1) at 35 °C for 14d with Co(2+). The binding properties of the metal were dependent on the structure of polyaza-macrocycles that were confirmed by the DFT optimized structure of two macrocycles. A detailed investigaton of UV-visible spectra of macrocycles and their complete interpretation with the help of TD-DFT along with the frontier molecular orbital calculations are presented.

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.

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.

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.