Sustainable nanotechnology decision support system: bridging risk management,sustainable innovation and risk governance

The significant uncertainties associated with the (eco)toxicological risks of engineered nanomaterials pose challenges to the development of nano-enabled products toward greatest possible societal benefit. This paper argues for the use of risk governance approaches to manage nanotechnology risks and sustainability, and considers the links between these concepts. Further, seven risk assessment and management criteria relevant to risk governance are defined: (a) life cycle thinking, (b) triple bottom line, (c) inclusion of stakeholders, (d) risk management, (e) benefit–risk assessment, (f) consideration of uncertainty, and (g) adaptive response. These criteria are used to compare five well-developed nanotechnology frameworks: International Risk Governance Council framework, Comprehensive Environmental Assessment, Streaming Life Cycle Risk Assessment, Certifiable Nanospecific Risk Management and Monitoring System and LICARA NanoSCAN. A Sustainable Nanotechnology Decision Support System (SUNDS) is proposed to better address current nanotechnology risk assessment and management needs, and makes. Stakeholder needs were solicited for further SUNDS enhancement through a stakeholder workshop that included representatives from regulatory, industry and insurance sectors. Workshop participants expressed the need for the wider adoption of sustainability assessment methods and tools for designing greener nanomaterials.     

Rapid and facile synthesis of siliceous MCM-48 mesoporous materials

A rapid and facile synthesis of cubic MCM-48 mesoporous material based on the modification of St?ber synthesis in as little time as 30 minutes at room temperature is reported in this communication.     

Why the case for clean surfaces does not hold water: Structure and morphology of hydroxylated nickel oxide (1 1 1)

We report an experimental and theoretical analysis of the √3 × √3-R30° and 2 × 2 reconstructions on the NiO (1 1 1) surface combining transmission electron microscopy, X-ray photoelectron spectroscopy, and reasonably accurate density functional calculations using the meta-GGA hybrid functional TPSSh. While the main focus here is on the surface structure, we also observe an unusual step morphology with terraces containing only even numbers of unit cells during annealing of the surfaces. The experimental data clearly shows that the surfaces contain significant coverage of hydroxyl terminations, and the surface structures are essentially the same as those reported on the MgO (1 1 1) surface implying an identical kinetically-limited water-driven structural transition pathway. The octapole structure can therefore be all but ruled out for single crystals of NiO annealed in or transported through humid air. The theoretical analysis indicates, as expected, that simple density functional theory methods for such strongly-correlated oxide surfaces are marginal, while better consideration of the metal d-electrons has a large effect although it is still not perfect.     

Zn selective luminescent ‘off-on’ probes derived from diaryl oxadiazole and aza-15-crown-5

New photo-induced electron transfer (PET) probes OMOX and OBOX, carrying an additional binding site in the form of ‘oxadiazole nitrogen’ have been designed to evaluate binding interactions with biologically significant Li⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺, and Zn²⁺ including environmentally toxic Ba²⁺ and Cd²⁺ using optical spectral techniques. While Li⁺, Na⁺, and K⁺ did not appreciably perturb either the absorption or emission spectra, Ba²⁺, Ca²⁺, Mg²⁺, Zn²⁺, and Cd²⁺ induced slight red shifts (2-8 nm) in the UV-visible spectra as well as pronounced chelation induced enhanced fluorescence (CHEF). Both OMOX and OBOX exhibited the highest CHEF in contact with the zinc ion, whereas Ba²⁺, Ca²⁺, Mg²⁺, and Cd²⁺ induced relatively less emission enhancements. OBOX, which is a poorer emitter (Φ_f=0.0062) than OMOX (Φ_f=0.015), showed highly promising 160-fold emission enhancement in the presence of Zn²⁺. Potential, therefore is available in OBOX to function as a selective luminescent ‘off-on’ sensor for Zn²⁺ in the presence of coordinatively competing Ba²⁺, Ca²⁺, Mg²⁺, and Cd²⁺ ions.     

Substoichiometric determination of mercury with cetyltrimethylammonium bromide

A radiometric method based on substoichiometric isotope dilution analysis has been developed for the determination of mercury using cetyltrimethylammonium bromide (CTAB) as the substoichiometric reagent. The method is based on the extraction of mercury as an ionassociation complex of tetraiodomercurate(II) ion with a substoichiometric amount of CTAB in benzene. The calibration graph was found to be linear in the range 0–10 μg Hg (II) in the aqueous phase of 10 ml volume. A detection limit of 0.06 μg·ml⁻¹ could be achieved by the proposed method. The relative standard deviation of the method was found to be 3.0% and the method has been successfully applied to study the determination of mercury in various synthetic mixtures.     

Evaluating the Free Energies of Solvation and Electronic Structures of Lithium‐Ion Battery Electrolytes

Adaptive biasing force molecular dynamics simulations and density functional theory calculations were performed to understand the interaction of Li⁺ with pure carbonates and ethylene carbonate (EC)‐based binary mixtures. The most favorable Li carbonate cluster configurations obtained from molecular dynamics simulations were subjected to detailed structural and thermochemistry calculations on the basis of the M06‐2X/6‐311++G(d,p) level of theory. We report the ranking of these electrolytes on the basis of the free energies of Li‐ion solvation in carbonates and EC‐based mixtures. A strong local tetrahedral order involving four carbonates around the Li⁺ was seen in the first solvation shell. Thermochemistry calculations revealed that the enthalpy of solvation and the Gibbs free energy of solvation of the Li⁺ ion with carbonates are negative and suggested the ion–carbonate complexation process to be exothermic and spontaneous. Natural bond orbital analysis indicated that Li⁺ interacts with the lone pairs of electrons on the carbonyl oxygen atom in the primary solvation sphere. These interactions lead to an increase in the carbonyl (C=O) bond lengths, as evidenced by a redshift in the vibrational frequencies [ν(C=O)] and a decrease in the electron density values at the C=O bond critical points in the primary solvation sphere. Quantum theory of atoms in molecules, localized molecular orbital energy decomposition analysis (LMO‐EDA), and noncovalent interaction plots revealed the electrostatic nature of the Li⁺ ion interactions with the carbonyl oxygen atoms in these complexes. On the basis of LMO‐EDA, the strongest attractive interaction in these complexes was found to be the electrostatic interaction followed by polarization, dispersion, and exchange interactions. Overall, our calculations predicted EC and a binary mixture of EC/dimethyl carbonate to be appropriate electrolytes for Li‐ion batteries, which complies with experiments and other theoretical results.     

Conformational isomerism and weak molecular and magnetic interactions in ternary copper(II) complexes of [Cu(AA)L']ClO4.nH2O, where AA = L-phenylalanine and L-histidine, L' = 1,10-phenanthroline and 2,2-bipyridine, and n = 1 or 1.5: synthesis, single-crystal X-ray structures, and magnetic resonance investigations

Weak molecular and magnetic exchange interactions in ternary copper(II) complexes, viz., [Cu(L-phe)(phen)(H(2)O)]ClO(4) (1), [Cu(L-phe)(bpy)(H(2)O)]ClO(4) (2), and [Cu(L-his)(bpy)]ClO(4).1.5H(2)O (3), where L-phe = L-phenylalanine, L-his = L-histidine, phen = 1,10-phenanthroline, and bpy = 2,2'-bipyridine, have been investigated. Single-crystal X-ray structures reveal that complex 2 crystallizes in a monoclinic space group P2(1), with unit cell parameters a = 7.422(7) A, b = 11.397(5) A, c = 12.610(2) A, beta = 102.10(5) degrees, V = 1043.0(11) A(3), Z = 2, R = 0.0574, and R(w) = 0.1657. Complex 3 crystallizes in a monoclinic space group C2, with a = 18.834(6) A, b = 10.563(4) A, c = 11.039(3) A, beta = 115.23(2) degrees, V = 1986.6(11) A(3), Z = 4, R = 0.0466, and R(w) = 0.1211. Molecules of 2, in the solid state, are self-assembled via weak intra- and intermolecular pi-pi stacking and H-bonding interactions. Molecules of 3 exhibit intermolecular dimeric association with the Cu.Cu separation being 3.811 A. X-ray structures and (1)H NMR studies reveal conformational isomerism in both solid and liquid states of complexes 1 and 2. The aromatic side chain of L-phe in 1 and 2 adopts either a "folded" (A) or an "extended" (B) conformation. Variable-temperature (1)H NMR and spin lattice relaxation measurements point out interconversion between conformations A and B at temperatures above 323 K. The change in molecular conformation induces a change in the electron density at the site of copper and band gap energy between HOMO and LUMO orbitals. Interestingly, in spite of paramagnetic nature, complexes 1 and 2 are amenable for both EPR and (1)H NMR spectroscopic studies. Single-crystal EPR spectra of 2 in three orthogonal planes are consistent with three-dimensional magnetic behavior. Intramolecular exchange dominates the dipolar interactions. The EPR spectra of 3 correspond to weak magnetic interactions between associated dimeric units. The structural and magnetic resonance investigations together reveal that the weak pi-pi stacking interactions are the electronic pathways for magnetic interactions in 1-3.     

STUDIES ON THE REACTIVITY PATTERNS OF HETEROCYCLICS IN AQUEOUS DMSO‐INTERACTION BETWEEN POSITIVE END OF SULFOXIDE DIPOLE AND LONE PAIR ON RING NITROGEN IN PYRIDINE DERIVATIVES

Abstract

The signals for the α, β, and γ protons of pyridine exhibit a downfield shift in DMSO-d₆, compared to CCl₄ as solvent, the order being γ > β > α. This is attributed to an interaction between the positive end of the DMSO dipole and the lone pair of electrons on the ring nitrogen. This effect is also reflected in the faster rate of alkaline hydrolysis of ethyl isonicotinate over ethyl nicotinate and ethyl picolinate in aqueous DMSO relative to aqueous ethanol. Similar solvent effects are also observed in the pmr spectrum of pyrazine.