Polyammonium derivatives of (thia)calix[4]arene: Synthesis and interaction with nucleic acids

© 2015 Nova Science Publishers, Inc. Targeted delivery of polynucleic acids in cells (transfection) for therapeutic purposesis limited by a number of obstacles, starting from the cell membrane to the geneexpression. To overcome the cell barriers, the use of gene carriers - viral and non-viralvectors are employed. One of the current approaches employed in the development ofsynthetic nonviral vectors is the functionalization of easily accessible molecularplatforms with receptor groups (amino, ammonium or guanidinium groups), capable ofinteracting with nucleic acids.In this chapter, we examine recent advances in the design and development ofsynthetic vectors, and the principles underlying their interactions with nucleic acids. Thefocus will be on recent advances in the design and synthesis of potential transfectionagents based on the (thia)calixarene platform functionalized with different polyaminofragments differing in the number of amino groups, the length of their alkyl linker chainsand the present or absent of hydroxy groups. The interaction of functionalized(thia)calixarene derivatives with DNA will also be discussed

Magnetic properties of the spin-1 chain compound NiCl3_3C6_6H5_5CH2_2CH2_2NH3_3

We report experimental results of the static magnetization, ESR and NMR spectroscopic measurements of the Ni-hybrid compound NiCl$_3$C$_6$H$_5$CH$_2$CH$_2$NH$_3$. In this material NiCl$_3$ octahedra are structurally arranged in chains along the crystallographic $a$-axis. According to the static susceptibility and ESR data Ni$^{2+}$ spins $S = 1$ are isotropic and are coupled antiferromagnetically (AFM) along the chain with the exchange constant $J = 25.5$ K. These are important prerequisites for the realization of the so-called Haldane spin-1 chain with the spin-singlet ground state and a quantum spin gap. However, experimental results evidence AFM order at $T_{\rm N} \approx 10$ K presumably due to small interchain couplings. Interestingly, frequency-, magnetic field-, and temperature-dependent ESR measurements, as well as the NMR data, reveal signatures which could presumably indicate an inhomogeneous ground state of co-existent mesoscopically spatially separated AFM ordered and spin-singlet state regions similar to the situation observed before in some spin-diluted Haldane magnets

p-tert-butyl thiacalix[4]arene derivatives functionalized in the lower rim with bis(3-aminopropyl)amine: Synthesis and interaction with DNA

© ISUCT Publishing. New tetrasubstituted derivatives of thiacalix[4]arene functionalized with bis(3-aminopropyl)amide fragments at the lower rim in the cone and 1,3-alternate conformations have been synthesized. It was demonstrated that the synthesized thiacalix[4]arenes derivatives interact with DNA resulting in a shift in absorption maxima to 257 nm with clear isosbestic point at 300 nm

Synthesis of p-tert-butylthiacalix[4]arenes functionalized with tris(2-aminoethyl)amine fragments at the lower rim and their interaction with model lipid membranes

© ISUCT Publishing. New tetrasubstituted derivatives of thiacalix[4]arene functionalized with tris(2-aminoethyl)amine fragments at the lower rim in the cone, partial cone and 1,3-alternate conformations have been synthesized. It has been shown that during the interaction of tris(2-aminoethyl)amine with thiacalix[4]arenes in cone and partial cone conformation, еру cyclic fragments are formed. The structure with acyclic fragments is obtained in the case of thiacalix[4]arenes in 1,3- alternate conformation. The interaction of these compounds with a biomembrane model system was studied. It has been shown that the interaction of these compounds with model lipid membranes depends not only on the presence of hydrophilic-hydrophobic groups but also on the spatial orientation of these groups

Aminophosphonates: Synthesis and practical application

There is an increasing interest in amine derivatives of phosphonic acids. The α- aminophosphonates, organophosphorus analogs of natural amino acids are most studied and attracted for the specialists in various branches of chemistry - biochemists, pharmacologists and synthetic chemists. Phosphonates containing the amine group in the β-position are less studied but recent studies suggest they may be useful as bioactive species and receptor compounds. Phosphonic acid derivatives are not only biologically active compounds but also effective extractants and membrane carriers for various substrates (metal ions, organic and inorganic acids, etc.). Many of these advantages are due to the combination of several different binding sites, namely, proton donating (NH) and two proton accepting groups (P=O and a lone electron pair of the nitrogen atom), as well as the possibility of varying the lipophilicity and sterical loading of the binding site. The acceptor phosphoryl group of the β-aminophosphonates is farther away from the nitrogen than that of the α-aminophosphonates. Hence the increased basicity of the nitrogen atom leads to the peculiar transport properties of these compounds. This chapter discusses the main methods for synthesizing α- and β-amine derivatives of phosphonic acids, their biological activity and the application of these compounds as extractants and membrane carriers. © 2012 by Nova Science Publishers, Inc. All rights reserved

Charge order and low frequency spin dynamics in lanthanum cuprates revealed by Nuclear Magnetic Resonance

We report detailed 17O, 139La, and 63Cu Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) measurements in a stripe ordered La1.875Ba0.125CuO4 single crystal and in oriented powder samples of La1.8-xEu0.2SrxCuO4. We observe a partial wipeout of the 17O NMR intensity and a simultaneous drop of the 17O electric field gradient (EFG) at low temperatures where the spin stripe order sets in. In contrast, the 63Cu intensity is completely wiped out at the same temperature. The drop of the 17O quadrupole frequency is compatible with a charge stripe order. The 17O spin lattice relaxation rate shows a peak similar to that of the 139La, which is of magnetic origin. This peak is doping dependent and is maximal at x ~ 1/8.Comment: submitted to European Physical Journal Special Topic

1/3 magnetization plateau and frustrated ferrimagnetism in a sodium iron phosphite

AT was supported by the Federal Ministry for Education and Research through the Sofja Kovalevskaya Award of Alexander von Humboldt Foundation. This work was supported in part by Russian Foundation for Basic Research grants 14-02-00111, 14-02-00245, 16-02-00021, from the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» (№ К2-2015-075 and № K4-2015-020) and by Act 211 of the Government of Russian Federation, agreement № 02.A03.21.0006. EAZ, JW and RK acknowledge support by the Excellence Initiative of the German Federal Government and States. PL thanks EPSRC (EP/K503162/1) for partial support of a studentship to IM and the Leverhulme Trust for the award of a post-doctoral fellowship (RPG-2013-343) to LC. SK is grateful for the funding by SSP1458 of the DFG.The sodium-iron phosphite NaFe3(HPO3)2(H2PO3)6 is studied by ac-magnetic susceptibility, pulsed-field magnetization, specific heat, and high-frequency electron spin resonance (HF-ESR) measurements combined with Mössbauer spectroscopy and density-functional calculations. We show that this compound develops ferrimagnetic order below TC = 9.5 K and reveals a magnetization plateau at 1/3-saturation. The plateau extends to Bc ~ 8 T, whereas above Bc the magnetization increases linearly until reaching saturation at Bs ~ 27 T. The Mössbauer spectroscopy reveals two magnetically non-equivalent iron sites with the 2:1 ratio. The HF-ESR spectra are consistent with a two-sublattice ferrimagnet and additionally pinpoint weak magnetic anisotropy as well as short-range spin order that persists well above TC. The ferrimagnetic order in the title compound is stabilized by a network of purely antiferromagnetic exchange interactions. The spin lattice comprises layers coinciding with the crystallographic (10-1) planes, with stronger couplings Ji ~ 1.5 K within the layers and weaker couplings Ji = 0.3−0.4 K between the layers. Both intralayer and interlayer couplings are frustrated. The ensuing ferrimagnetic order arises from a subtle interplay of the frustrated but nonequivalent exchange couplings.PostprintPostprintPeer reviewe