Organotin(IV) complexes of NSAID,ibuprofen, X-ray structure of Ph3Sn(IBF), binding and cleavage interaction with DNA and in vitro cytotoxic studies of several organotin complexes of drugs

This study encompasses the synthesis and characterization of organotin(IV) derivatives of non-steroidal anti-inflammatory drug ibuprofen (IBF), viz. [(Me₃Sn)(IBF)] ( 1 ), [(Bu₃Sn)(IBF)] ( 2 ), [Ph₃Sn(IBF)] ( 3 ), {[Me₂Sn(IBF)]₂O}₂ ( 4 ) and [Bu₂Sn(IBF)₂] ( 5 ). The crystal structure of complex 3 , [Ph₃Sn(IBF)], indicates a highly distorted tetrahedral (td) geometry with anisobidentate mode of coordination of the carboxylate group with tin atom, and a similar structure has been proposed for other two triorganotin(IV) derivatives. Moreover, the DFT (density functional theory) calculation and other studies have verified a dimer distannoxane type of structure for complex 4 , {[Me₂Sn(IBF)]₂O}₂. Complex 5 has been found to exhibit a highly distorted octahedral geometry around the tin atom. To investigate the DNA binding profile of the synthesized complexes, viscosity measurement, UV–vis and fluorescence titrations were performed, which revealed an intercalative type of binding with DNA for IBF and complex 5 and external binding in case of the complexes 1 and 2 ; complexes 3 and 4 could not be studied owing to their insufficient solubility in tris buffer. Plasmid DNA fragmentation studies of IBF and complexes 1 , 2 and 5 indicate that they cleaved the pBR322 plasmid potentially. Further, the drugs IBF {2-[4-(2-methylpropyl)phenyl]propanoic acid}, MESNA (sodium 2-mercaptoethane-sulfonate), warfarin [2H-1-benzopyran-2-one,4-hydroxy-3-(3-oxo-1-phenylbutyl)], sulindac (2-{5-fluoro-1-[(4-methanesulfinylphenyl) methylidene]-2-methyl-1H-inden-3-yl}acetic acid) and their corresponding organotin(IV) complexes 1–19 (complexes 6–19 were synthesized/reported previously) were screened in vitro for cytotoxicity against human cancer cell lines viz. DU145 (prostate cancer), HCT-15 (colon adenocarcinoma), Caco-2 (colorectal adenocarcinoma), MCF-7 (mammary cancer), LNCaP (androgen-sensitive prostate adenocarcinoma) and HeLa (cervical cancer), through MTT reduction assay and the cause of cell death was investigated through acridine orange/ethidium bromide staining of cells and DNA fragmentation assay. The probable structure–cytotoxicity relationship is also discussed. The major role of apoptosis along with small necrosis was also validated by flow cytometry assay using annexin V–fluorescein isothiocyanate and propidium iodide analysis.     

Soft Phonon Modes Leading to Ultralow Thermal Conductivity and High Thermoelectric Performance in AgCuTe

Crystalline solids with intrinsically low lattice thermal conductivity (κ_L) are crucial to realizing high‐performance thermoelectric (TE) materials. Herein, we show an ultralow κ_L of 0.35 Wm^?1 K^?1 in AgCuTe, which has a remarkable TE figure‐of‐merit, zT of 1.6 at 670 K when alloyed with 10 mol % Se. First‐principles DFT calculation reveals several soft phonon modes in its room‐temperature hexagonal phase, which are also evident from low‐temperature heat‐capacity measurement. These phonon modes, dominated by Ag vibrations, soften further with temperature giving a dynamic cation disorder and driving the superionic transition. Intrinsic factors cause an ultralow κ_L in the room‐temperature hexagonal phase, while the dynamic disorder of Ag/Cu cations leads to reduced phonon frequencies and mean free paths in the high‐temperature rocksalt phase. Despite the cation disorder at elevated temperatures, the crystalline conduits of the rigid anion sublattice give a high power factor.     

Ruthenium(II)‐Catalyzed Synthesis of Spirobenzofuranones by a Decarbonylative Annulation Reaction

The first decarbonylative insertion of an alkyne through C?H/C?C activation of six‐membered compounds is reported. The Ru‐catalyzed reaction of 3‐hydroxy‐2‐phenyl‐chromones with alkynes works most efficiently in the presence of the ligand PPh₃ to provide spiro‐indenebenzofuranones. Unlike previously reported metal‐catalyzed decarbonylative annulation reactions, in the present decarbonylative annulation reaction, the annulation occurs before extrusion of carbon monoxide.     

Alkali metals in silica gel (M-SG): a new reagent for desulfonation of amines

A novel method for the desulfonation of secondary amines is described. Alkali metals absorbed into nanostructured silica (M-SG) were found to be useful solid-state reagents for the desulfonation of a range of N,N-disubstituted sulfonamides. M-SG reagents are room-temperature-stable free-flowing powders that retain the chemical reactivity of the parent metal, decreasing the danger and associated cost of using reactive metals.     

Binding of hairpin polyamides to DNA studied by fluorescence correlation spectroscopy for DNA nanoarchitectures

We have recently constructed a “DNA strut” consisting of two DNA-binding hairpin polyamides of Dervan-type connected via a long flexible linker and were able to show that this strut can be used to sequence-selectively connect DNA helices. This approach provides a second structural element (besides the Watson–Crick base pairing) for the assembly of higher-order DNA nanoarchitectures from smaller DNA building blocks. Since none of the existing analytical techniques for studying this kind of system were found suitable for detection and quantification of the formation of the resulting complexes, we chose fluorescence correlation spectroscopy (FCS). In the present study we show that FCS allowed us in a versatile and fast way to investigate the binding of Dervan polyamides to DNA. In particular it also shows its power in the quantitative detection of the formation of multimeric complexes and the in investigation of binding under nonphysiological conditions. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Assembling metals (Co II and Mn II) with pyridylcarboxylates in the presence of azide: synthesis, structural aspects and magnetic behavior of three coordination polymers

The reaction between Co(NO3)2.6H2O and substituted pyridylcarboxylic acid [nicotinic acid (Hnic) or trans-3-pyridylacrylic acid (Htpa)] in the presence of NaN3 under hydrothermal conditions yielded [Co(1.5)(nic)2 (Hnic)(N3)]n (1) and [Co(1.5)(tpa)2 (N3)(H2O)]n (2), respectively. Single crystal structure analyses reveal that both complexes are 3D complicated coordination polymers. The basic repeating units in both of the complexes are Co(3) trinuclear clusters containing syn-syn bridging carboxylate and end-on azido linker. A similar reaction using MnCl2.4H2O in presence of equimolar amounts of Htpa and NaN3 yielded a 2D corrugated sheet [Mn(tpa)2]n (3) containing no azide. Complex 3 can also be synthesized under hydrothermal conditions using Natpa in the absence of NaN3. Surprisingly, the same reaction at room temperature yielded a known mononuclear complex [Mn(tpa)2(H2O)4]. Variable temperature magnetic studies down to 2 K revealed the dominant antiferromagnetic nature of the first two complexes with a ferrimagnetic type of behavior despite the facts that they are homometallic and homospin systems. The susceptibility data in both cases were analyzed by a Co3 trinuclear model as well as considering inter-trimer interactions. Complex 3 is weakly antiferromagnetic in nature with an exchange parameter of J = -2 cm(-1) through the syn-anti bridging carboxylate pathway.     

Energetics and role of the hydrophobic interaction during photoreaction of the BLUF domain of AppA

A recently developed method for time-resolved thermodynamic measurements was used to study the photochemical reaction(s) of the BLUF domain of AppA (AppA-BLUF), which has a dimeric form in the ground state, in terms of the energetics and heat capacity changes (DeltaC(p)) in different time domains. The enthalpy change (DeltaH) of the first intermediate that forms within 1 ns after photoexcitation was 38 (+/-8) kJ mol(-1) at 298 K. The heat capacity change (DeltaC(p)) upon formation of this intermediate was positive [1.4 (+/-0.3) kJ mol(-1) K(-1)]. This positive DeltaC(p) suggests that the hydrophobic surface area of AppA-BLUF exposed to the bulk solvent increased. After this initial transition, a dimerization reaction with another ground-state dimer (i.e., tetramer formation) takes place. Upon this reaction, the energy was stabilized to 26 (+/-6) kJ mol(-1) at 298 K. Interestingly, the dimer formation was accompanied by a larger but negative DeltaC(p) [-6.0 (+/-1) kJ mol(-1) K(-1)]. This negative DeltaC(p) might indicate buried hydrophobic residues at the interface of the dimer and/or the existence of trapped water at the interface. We suggest that hydrophobic interactions are the main driving force for the formation of the dimer upon photoactivation of AppA-BLUF.     

A highly enantioselective chiral Schiff-base fluorescent sensor for mandelic acid

A chiral Schiff-base compound, 4-methyl-2,6-bis-[(2-hydroxy-1-phenylethylimino)methyl]phenol, is found to act as highly enantioselective fluorescent agent for α-hydroxycarboxylic acid, e.g., mandelic acid. It is observed that, within a certain concentration range, one enantiomer of the chiral acid can increase the fluorescence intensity of the Schiff-base compound 122-fold while the other enantiomer enhances the intensity only 42-fold. Such highly enantioselective responses towards the chiral acid make the unusual Schiff-base compound attractive as a fluorescent sensor for determining the enantiomeric composition of α-hydroxycarboxylic acids.     

Influence of Potassium Metal-Support Interactions on Dendrite Growth

Combined synchrotron X-ray nanotomography imaging, cryogenic electron microscopy (cryo-EM) and modeling elucidate how potassium (K) metal-support energetics influence electrodeposit microstructure. Three model supports are employed: O-functionalized carbon cloth (potassiophilic, fully-wetted), non-functionalized cloth and Cu foil (potassiophobic, nonwetted). Nanotomography and focused ion beam (cryo-FIB) cross-sections yield complementary three-dimensional (3D) maps of cycled electrodeposits. Electrodeposit on potassiophobic support is a triphasic sponge, with fibrous dendrites covered by solid electrolyte interphase (SEI) and interspersed with nanopores (sub-10 nm to 100 nm scale). Lage cracks and voids are also a key feature. On potassiophilic support, the deposit is dense and pore-free, with uniform surface and SEI morphology. Mesoscale modeling captures the critical role of substrate-metal interaction on K metal film nucleation and growth, as well as the associated stress state.