Exploiting phenyl embraces and pi-stacking in the assembly of arrays of tetraphenylphosphonium p-sulfonatocalix[4]arene

Phenyl embraces involving tetraphenylphosphonium cations feature in complexes of p-sulfonatocalix[4]arene where a phenyl ring of a cation is included in the cavity of the calixarene. The overall structures are based on pseudo-polymorphic supramolecular arrays and their formation is templated or induced by lanthanide ions.     

Inter-digitation approach to encapsulation of C60: [C60 [symbol: see text] (p-phenylcalix[5]arene)2

p-Phenylcalix[5]arene shows a strong and selective binding of C60 in toluene resulting in crystallisation of a hemispherically inter-digitated 2:1 complex; the receptor itself crystallizes from toluene with self assembly through phenyl group inclusion.     

Polymorphism in Lithium Amides: A Structural and Theoretical Study. Synthesis, Mechanism, and NMR Studies of the Lithiation of N,N'-Di-tert-butylethylenediamine

The lithiation of N,N'-di-tert-butylethylenediamine by MeLi in benzene has been shown by (1)H NMR spectroscopy to proceed via the partially lithiated species [cis-{Li[&mgr;-N(t-Bu)CH(2)CH(2)N(H)t-Bu]}(2)], 2, and [{Li[N(t-Bu)CH(2)CH(2)N(H)t-Bu]}(2)Li{N(t-Bu)CH(2)CH(2)Nt-Bu}Li], 3, prior to the formation of the dilithiated species {Li[N(t-Bu)CH(2)CH(2)Nt-Bu]Li}, 4. The solid state structures of 2, 3, and a dimeric form of 4 (4a) have been determined. A sparingly soluble form of 4 (4b) has also been isolated which has a proposed polymeric ladder structure. These structures are discussed with respect to the alternatives available for the aggregation of the dilithiated species; stacking to form dimeric Li(4)N(4) cages and laddering to form Li(n)()N(n)() ladders. Ab initio molecular orbital calculations give insight into the energetics of these aggregates and the possible structures adopted by solvated and unsolvated dilithium ethylenediamide complexes. Crystals of 2 are monoclinic, of space group C2/c (No. 15), a = 19.222(7), b = 8.734(2), c = 17.149(5) ?, beta = 119.40(1) degrees, Z = 4. Crystals of 3are monoclinic, of space group P2(1)/c (No. 14), a = 9.836(8), b = 17.821(3), c = 21.78(2) ?, beta = 101.57(4) degrees, Z = 4. Crystals of 4a are monoclinic, of space group P2(1)/c (No. 14), a = 15.990(7), b = 10.0162(9), c = 16.42(1) ?, beta = 104.49(2) degrees, Z = 4. Crystals of 6 are monoclinic, of space group P2(1)/c (No. 14), a = 10.124(8), b = 17.861(3), c = 22.21(2) ?, beta = 102.05(4) degrees, Z = 4.     

The effect of arsenic exposure on the biochemical and mineral contents of Labeo rohita bones: An FT-IR study

Arsenic compounds are ubiquitous and widespread in the environment as a result of natural or anthropogenic occurrence. Fish are the major source of protein for human consumption. They are also a source of contamination, because of the amounts of heavy elements they can contain, some of which are highly toxic. Fish bones are high in calcium, which is an essential mineral for normal body function. It consists of water, organic material, and mineral matter. Chelating agents have been used clinically as antidotes for acute and chronic metal intoxications. In the present study, an attempt is made to investigate the bio-accumulation of arsenic and its effect on the biochemical and mineral contents of Labeo rohita bones using, Fourier transform infrared (FT-IR) spectroscopy. The results of the present study indicate that arsenic exposure induces significant reduction on the biochemical and mineral contents of the L. rohita bones. Further, the DMSA treatment significantly improves these levels. This shows that DMSA is an effective chelator for arsenic toxicity. Quantitative curve-fitting analyses of amide I band have proved useful in studying the nature and the extent of protein conformational changes. A decrease in α-helical and random coil structures and an increase in β-sheet structures have been observed due to arsenic exposure. In conclusion, the present study shows that the FT-IR spectroscopy coupled with second derivative and curve-fitting analysis gives useful information about the biochemical and mineral contents of the L. rohita bones.     

FTIR study of zinc-induced biochemical changes in the liver of Indian carp <Emphasis Type="Italic">Labeo rohita</Emphasis>

Zinc is an essential metal for different physiological functions and becomes toxic when elevated concentrations are introduced into the environment. In the present study, an attempt is made to analyze zinc-induced biochemical changes in the liver tissues of freshwater fingerlings of Labeo rohita using Fourier Transformation Infrared Spectroscopy. Several important features have been observed in the FTIR spectra of zinc-intoxicated liver tissues, namely, altered membrane lipid, altered protein profile, and increased glycogen content, indicating an alteration in the lipid and protein profiles leading to modification in membrane composition. Further, it is observed that acute exposure to zinc causes some alteration in protein profile with a decrease in α-helix and an increase in random coil structure. Treatment with the chelating agent D-penicillamine reduces the biochemical contents in the liver tissues. This shows that D-penicillamine is a good antidote for zinc toxicity. Published in Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 746–752, September–October, 2008.     

Horning-crown macrocycles: novel hybrids of calixarenes and crown ethers

[reaction: see text] Novel macrocycles possessing ether linkages and 2,6-disubstituted phenolics were produced in one step and with 100% atom economy by isoaromatization of chameleon macrocyclic precursors possessing 2,6-diarylidenecyclohexanone moieties. Intramolecular hydrogen bonding of the phenolic hydrogen atoms influenced the shape of the macrocycles and dictated host-guest behavior.     

Conformation perturbation of p-sulfonatocalix[5]arene via complexation of 1,4-diazabicyclo[2.2.2]octane

A novel conformation of p-sulfonatocalix[5]arene has been established in the solid state with two calixarenes organised in a 'bis-molecular capsule' shrouding two di-protonated DABCO molecules and two water molecules within.     

Toward mimicking viral geometry with metal-organic systems

Icosahedral and cuboctahedral arrangements of calixarenes, a nanometer-scale, spheroidal assembly of 12 calixarene molecules, can be manipulated in a highly controlled fashion. Previously, such assemblies were observed to favor placement of the calixarenes at the vertexes of an icosahedron. A supramolecular constraint is employed in order to enforce molecular alignment and produce a cuboctahedral arrangement. The internal volume of the cuboctahedron is approximately 30% greater than that of the icosahedron. Furthermore, in stark contrast to that of the icosahedral Platonic solid, the shell of the cuboctahedral Archimedean solid is porous.     

Characterisation of a new 1:1 (C60)(CHBr3) intercalation complex

The 1:1 crystalline intercalation complex (C60)(CHBr3) is an entirely new type of fullerene-haloform complex with an irregular structure comprised of C60 molecules interspersed with zigzag chains of disordered bromoform molecules.