Variation in the Biomolecular Interactions of Nickel(Ii) Hydrazone Complexes Upon Tuning the Hydrazide Fragment

Three new bivalent nickel hydrazone complexes have been synthesised from the reactions of [NiCl2(PPh3)(2)] with H2L {L = dianion of the hydrazones derived from the condensation of o-hydroxynaphthaldehyde with furoic acid hydrazide (H2L1) (1)/thiophene-2-acid hydrazide (H2L2) (2)/isonicotinic acid hydrazide (H2L3) (3)} and formulated as [Ni(L-1)(PPh3)] (4), [Ni(L-2)(PPh3)] (5) and [Ni(L-3)(PPh3)] (6). Structural characterization of these compounds 4-6 were accomplished by using various physico-chemical techniques. Single crystal X-ray diffraction data of complexes 4 and 5 proved their distorted square planar geometry. In order to ascertain the potential of the above synthesised compounds towards biomolecular interactions, additional experiments involving interaction with calf thymus DNA (CT DNA) and bovine serum albumin (BSA) were carried out. All the ligands and corresponding nickel(II) chelates have been screened for their scavenging effect towards O-2(-), OH and NO radicals. The efficiency of complexes 4-6 to arrest the growth of HeLa, HepG-2 and A431 tumour cell lines has been studied along with the cell viability test against the non-cancerous NIH 3T3 cells under in vitro conditions.University Grants Commission, New Delhi under the UGC-SAP-DRSRobert A. Welch Foundation F-0003Chemistr

Sequential decarboxylative azide–alkyne cycloaddition and dehydrogenative coupling reactions: one-pot synthesis of polycyclic fused triazoles

Herein, we describe a one-pot protocol for the synthesis of a novel series of polycyclic triazole derivatives. Transition metal-catalyzed decarboxylative CuAAC and dehydrogenative cross coupling reactions are combined in a single flask and achieved good yields of the respective triazoles (up to 97% yield). This methodology is more convenient to produce the complex polycyclic molecules in a simple way

Tetra­kis(1,3,4,6,7,8-hexa­hydro-2H-pyrimido[1,2-a]pyrimidin-9-ido-κ2 N 1,N 9)niobium(V) hexa­fluorido­phosphate

The title complex, [Nb(C7H12N3)4]PF6, features chelating hpp anions (hpp is 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrim­idine) that define a distorted dodeca­hedral coordination geometry based on an N8 donor set. The Nb atom is situated on a site of symmetry , and the PF6 − anion has crystallographic fourfold symmetry

Gyroscope like molecules consisting of trigonal or square planar osmium rotators within three-spoked dibridgehead diphosphine stators: syntheses, substitution reactions, structures, and dynamic properties

Reactions of (NH4)2OsX6 (X = Cl, Br) with CO and the phosphines P((CH2)mCH[double bond, length as m-dash]CH2)3 (m = 6, a; 7, b; 8, c) give cis,cis,trans-Os(CO)2(X)2(P((CH2)mCH[double bond, length as m-dash]CH2)3)2 (46–73%). These are treated with Grubbs’ catalyst (7 mol%, 0.0010 M, C6H5Cl). Subsequent hydrogenations (PtO2) yield the gyroscope like complexes cis,cis,trans-Os(CO)2(X)2(P((CH2)n)3P) (n = 2m + 2; X = Cl, 6a–c; Br, 7a–c; 5–31%) and the isomers cis,cis,trans-Os(CO)2(X)2(P(CH2)n−1CH2)((CH2)n)(P(CH2)n−1CH2) (X = Cl, 6′a–c; Br, 7′a–c; 12–51%) derived from a combination of interligand and intraligand metatheses. Reductions of 6a,c, 6′b, and 7′b with C8K under CO atmospheres afford trans-Os(CO)3(P((CH2)n)3P) (9a,c, 79–82%) and trans-Os(CO)3(P(CH2)15CH2)((CH2)16)(P(CH2)15CH2) (9′b, 53–84%). Reaction of 9a and CF3SO3H yields the cationic hydride complex mer,trans-[Os(H)(CO)3(P((CH2)14)3P)]+ CF3SO3− (9a-H+ CF3SO3−; quantitative by NMR). Preparative reactions of 9a,c or 9′b and [H(OEt2)2]+ BArf− (BArf− = B(3,5-C6H3(CF3)2)4−) afford 9a,c-H+ BArf− (80%) or 9′b-H+ BArf− (68%). Reactions of 6a, 6′b, and 7a with MeLi or PhLi give cis,cis,trans-Os(CO)2(Me)2(P((CH2)14)3P) (11a, 98%), cis,cis,trans-Os(CO)2(Me)2(P(CH2)15CH2)((CH2)16)(P(CH2)15CH2) (98%), and cis,cis,trans-Os(CO)2(Ph)2(P((CH2)14)3P) (12a, 58%). NMR data for 6a–c, 7a–c, 9a,c, 9a,c-H+ X−, and 11a indicate that rotation of the OsLy moieties is fast on the NMR time scale at room temperature. In contrast, the phenyl groups in 12a act as “brakes” and two sets of 13C NMR signals are observed for the methylene chains (2 : 1). The crystal structures of 6a–c, 7b,c, 7′a, 9a, 9a-H+ BArf−, 11a, and 12a are analyzed with respect to OsLy rotation in solution and the solid state

Syntheses, structures, and stabilities of aliphatic and aromatic fluorous iodine(I) and iodine(III) compounds::the role of iodine Lewis basicity

The title molecules are sought in connection with various synthetic applications. The aliphatic fluorous alcohols RfnCH2OH (Rfn = CF3(CF2)n–1; n = 11, 13, 15) are converted to the triflates RfnCH2OTf (Tf2O, pyridine; 22–61%) and then to RfnCH2I (NaI, acetone; 58–69%). Subsequent reactions with NaOCl/HCl give iodine(III) dichlorides RfnCH2ICl2 (n = 11, 13; 33–81%), which slowly evolve Cl2. The ethereal fluorous alcohols CF3CF2CF2O(CF(CF3)CF2O)xCF(CF3)CH2OH (x = 2–5) are similarly converted to triflates and then to iodides, but efforts to generate the corresponding dichlorides fail. Substrates lacking a methylene group, RfnI, are also inert, but additions of TMSCl to bis(trifluoroacetates) RfnI(OCOCF3)2 appear to generate RfnICl2, which rapidly evolve Cl2. The aromatic fluorous iodides 1,3-Rf6C6H4I, 1,4-Rf6C6H4I, and 1,3-Rf10C6H4I are prepared from the corresponding diiodides, copper, and RfnI (110–130 °C, 50–60%), and afford quite stable RfnC6H4ICl2 species upon reaction with NaOCl/HCl (80–89%). Iodinations of 1,3-(Rf6)2C6H4 and 1,3-(Rf8CH2CH2)2C6H4 (NIS or I2/H5IO6) give 1,3,5-(Rf6)2C6H3I and 1,2,4-(Rf8CH2CH2)2C6H3I (77–93%). The former, the crystal structure of which is determined, reacts with Cl2 to give a 75:25 ArICl2/ArI mixture, but partial Cl2 evolution occurs upon work-up. The latter gives the easily isolated dichloride 1,2,4-(Rf8CH2CH2)2C6H3ICl2 (89%). The relative thermodynamic ease of dichlorination of these and other iodine(I) compounds is probed by DFT calculations

\u3ci\u3eWRTL\u3c/i\u3e and \u3ci\u3eRandall\u3c/i\u3e: The Roberts Court and the Unsettling of Campaign Finance Law

The first term of the Roberts Court was a potentially pivotal moment in campaign finance law. The Court both broke its pattern of deference to federal and state regulations that had marked the last half-dozen years and began to take a more critical approach to campaign finance restrictions. In Randall v. Sorrell, the Court struck down a Vermont law that sought to limit expenditures and to lower contributions in state and local elections. The expenditure restriction decision was no surprise, as it essentially reaffirmed the Court\u27s rejection of expenditure limits in Buckley v. Valeo three decades ago. But the ruling that Vermont\u27s contribution limits were too low marked the first time the Court had invalidated a contribution limit in a candidate election. Although Randall subjected contribution limits to closer scrutiny than in previous cases, the fragmented Court failed to articulate a clear standard of review. In Wisconsin Right to Life v. FEC ( WRTL ), the Court determined that the 2003 decision in McConnell v. FEC, rejecting a First Amendment challenge to the electioneering communication title of the Bipartisan Campaign Reform Act ( BCRA \u27) of 2002, only dealt with a facial attack, thus permitting an as-applied challenge. WRTL, thus, recognized the new and difficult question of determining when political ads that fall within the statutory definition electioneering ought nevertheless be exempt from election regulation. The Court, however, said nothing about the standards for determining when an as-applied exception should be granted. That question – and the long-term significance of the decision – may be resolved when the case returns to the Court this term. It is unclear whether Randall and WRTL simply mark the end of a period of judicial deference to new campaign finance limits or whether they signal the beginning of an era in which the Court will reconsider older decisions and move in a more sharply deregulatory direction. At the very least, the cases reopen old questions, create new uncertainties, and underscore the divisions within the Court concerning the constitutional framework for addressing campaign finance restrictions. Together, they provide new impetus to the idea that campaign finance reformers should redirect their energies away from limiting private funds and give greater attention to increasing the role of constitutionally unexceptionable public funds in our campaign finance system

Hydrogen bonds and dispersion forces serving as molecular locks for tailored Group 11 bis(amidine) complexes

A flexible polydentate bis(amidine) ligand LH2, LH2 = {CH2NH(tBu)C 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 N-2-(6-MePy)}2, operates as a molecular lock for various coinage metal fragments and forms the dinuclear complexes [LH2(MCl)2], M = Cu (1), Au (2), the coordination polymer [{(LH2)2(py)2(AgCl)3}(py)3]n (3), and the dimesityl-digold complex [LH2(AuMes)2] (4) by formal insertion of MR fragments (M = Cu, Ag, Au; R = Cl, Mes) into the N-H⋯N hydrogen bonds of LH2 in yields of 43-95%. Complexes 1, 2, and 4 adopt C2-symmetrical structures in the solid state featuring two interconnected 11-membered rings that are locked by two intramolecular N-H⋯R-M hydrogen bonds. QTAIM analyses of the computational geometry-optimized structures 1a, 2a, and 4a reveal 13, 11, and 22 additional bond critical points, respectively, all of which are related to weak intramolecular attractive interactions, predominantly representing dispersion forces, contributing to the conformational stabilization of the C2-symmetrical stereoisomers in the solid state. Variable-temperature 1H NMR spectroscopy in combination with DFT calculations indicate a dynamic conformational interconversion between two C2-symmetrical ground state structures in solution (ΔG‡c = 11.1-13.8 kcal mol−1), which is accompanied by the formation of an intermediate possessing Ci symmetry that retains the hydrogen bonds

Sequential decarboxylative azide–alkyne cycloaddition and dehydrogenative coupling reactions: one-pot synthesis of polycyclic fused triazoles

Herein, we describe a one-pot protocol for the synthesis of a novel series of polycyclic triazole derivatives. Transition metal-catalyzed decarboxylative CuAAC and dehydrogenative cross coupling reactions are combined in a single flask and achieved good yields of the respective triazoles (up to 97% yield). This methodology is more convenient to produce the complex polycyclic molecules in a simple way