Isabelle Mallard

Remediation technologies using cyclodextrins: an overview

Nowadays, the human activity and the modern way of life are responsible for the increase of the environmental pollution. Industrial processes generate a variety of molecules that may pollute air, water, and soils due to negative impacts for ecosystems and humans. The development of innovative remediation technologies has thus emerged as a significant environmental priority. Within this scope, supramolecular chemistry, which is a recent discipline, could provide solutions. In particular, cyclodextrins (CDs) are a family of cyclic oligosaccharides having a low-polarity cavity in which organic compounds of appropriate shape and size can form inclusion complexes. This unique property makes them suitable for application in environmental protection. Here, we review the use of cyclodextrins and cyclodextrin derivatives in remediation technologies. Accordingly, the present review shows the advantages of using CDs in soil, groundwater, wastewater, and atmosphere remediation. Resulting processes are highly versatile, since the complexing ability of CD is applicable to a wide range of pollutants. They may also been referred to green processes, according to the CD innocuity. Moreover, as inclusion phenomena correspond to reversible equilibriums, a major trend in the CD environmental application field is to develop methods, which combine supramolecular chemistry and irreversible processes, as advanced oxidation or biodegradation. Such processes might lead to a complete remediation of pollutants and eventually to the CD recycling.

A mild and efficient one-pot synthesis of 1-hydroxymethylene-1,1-bisphosphonic acids. Preparation of new tripod ligands

Abstract A simple and efficient one-pot procedure for synthesis of 1-hydroxymethylene-1,1-bisphosphonic acids by reaction of acyl chlorides and tris(trimethylsilyl)phosphite is described. This method was applied to the synthesis of new phosphonated chelating tripod ligands.

Retention of aroma compounds from Mentha piperita essential oil by cyclodextrins and crosslinked cyclodextrin polymers

In this paper, the controlled release of aroma compounds from cyclodextrins (CDs) and CD polymers was studied by multiple headspace extraction (MHE) experiments. Mentha piperita essential oil was obtained by Soxhlet extraction and identification of the major compounds was performed by GC-MS analysis. Menthol, menthone, pulegone and eucalyptol were identified as the major components. Retention of standard compounds in the presence of different CDs and CD polymers has been realised by static headspace gas chromatography (SH-GC) at 25 °C in the aqueous or gaseous phase. Stability constants for standard compounds and for compounds in essential oil have been also determined with monomeric CD derivatives. The obtained results indicated the formation of a 1:1 inclusion complex for all the studied compounds. Molecular modelling was used to investigate the complementarities between host and guest. This study showed that β-CDs were the most versatile CDs and that β-CD polymers could perform the controlled release of aroma compounds.

Cyclodextrins for Remediation Technologies

Human activity and the modern way of life are responsible for the increase of environmental pollution. Industrial processes generate many substances that pollute air, water and soils with negative impacts for ecosystems and humans. The development of innovative remediation technologies has thus emerged as a significant environmental priority. Supramolecular chemistry can provide promising remediation methods to solve pollution issues. In particular, cyclodextrins (CDs) are a family of cyclic oligosaccharides that are composed of α-1,4-linked glucopyranose subunits. Cyclodextrins have thus a low-polarity cavity in which organic pollutants of appropriate shape and size can form inclusion complexes. This unique property makes cyclodextrins suitable for application in environmental protection by pollutant trapping. Accordingly, the present review lists the advantages of using cyclodextrins in soil, groundwater, wastewater and atmosphere remediation. The inclusion mechanism have been used in soil, water and air, either as solubilizing agent when the cyclodextrin is diluted in aqueous solution, or as trapping agent when cyclodextrin is immobilized on various supports. Resulting processes are highly versatile, since the complexing ability of cyclodextrins includes a wide range of pollutants. Remediation using cyclodextrins is a green processe due to cyclodextrins innocuity. Moreover, since inclusion involves reversible equilibriums, a major trend in the cyclodextrin environmental application field is to develop methods that combine both supramolecular chemistry and irreversible processes such as advanced oxidation or biodegradation. Such processes could lead to a complete remediation of pollutants and to cyclodextrin recycling.

Cyclodextrins: A promising drug delivery vehicle for bisphosphonate

Bisphosphonates are well established pharmaceutical drugs with wide applications in medicine. Nevertheless, the side chain and the nature of phosphorous groups could induce a poor aqueous solubility and act on their bioavailability. At the same time, cyclodextrins are cage molecules that facilitate transport of hydrophobic molecules to enhance the intestinal drug absorption of these molecules by forming inclusion complexes. Here we demonstrate that cyclodextrins could be used as a bisphosphonate carrier. The formation of cyclodextrins-bisphosphonate complexes was characterized by 1D and 2D NMR spectroscopy, Isothermal Titration Calorimetry and UV-vis spectroscopy. The results revealed that only the side chain of bisphosphonate was involved in the inclusion phenomenon and its length was a crucial parameter in the control of affinity. Findings from this study suggest that cyclodextrin will be a useful carrier for bisphosphonates.

Synthesis and inclusion ability of anthracene appended β-cyclodextrins: unexpected effect of triazole linker

A new fluorescent β-cyclodextrin has been synthesized by coupling an anthracene moiety to the cyclic oligosaccharide via click chemistry. The influence of the triazole spacer was compared to the simple amino and amido linkers. While a sensing ability toward adamantan-1-ol was observed with the latter two spacers, the absence of inclusion capacity prevents the triazole modified cyclodextrin from showing any fluorescence variations. The difference in the binding behaviors studied by Isothermal Titration Calorimetry, UV-vis and fluorescence spectroscopies, was highlighted by the NOESY NMR spectra of the modified cyclodextrins: whereas a free cavity was observed for the amino and amido linkers, an important obstruction was obtained in the case of the triazole.

Cyclodextrin-intercalated layered double hydroxides for fragrance release

In order to attain the controlled release of fragrance, the intercalation of cyclodextrins (CDs) and fragrance in layered double hydroxides (LDHs) was examined. Carboxymethyl-β-CDs (CMCDs) of various degrees of substitution as well as Mg–Al support were synthesized. CMCDs were intercalated into LDH by the reconstruction method. Powder X-ray diffraction, thermal gravimetric analyses and Fourier transform infrared indicated a successful intercalation of CMCDs into the LDH gallery. The retention capacities of the hybrid materials were investigated in aqueous phase and in gaseous solution by static headspace gas chromatography and multiple headspace extraction. The functionalization of the LDH with CMCD allowed the encapsulation of various organic guests and could prolong the fragrance release time in comparison to that from LDH without CMCD, which can be attributed to the inclusion of the fragrance compound in the CMCD cavity.

p-SUBSTITUTED BENZYL HYDROXYBISPHOSPHONATES: SYNTHESIS AND HYDROLYSIS

Abstract Several hydroxybisphosphonate benzyl esters have been synthesized for study. The effect of the benzyl substituent on the acidic hydrolysis of the phosphonic esters has also been studied.

Recognition of iron ions by carbazole–desferrioxamine fluorescent sensor and its application in total iron detection in airbone particulate matter

This work reports on an efficient microwave irradiation synthesis of a new fluorescent chemosensor based on desferrioxamine B (DFO-B) and carbazole moiety. Furthermore, this novel chemosensor was employed for a comparative study of real environmental samples of airbone particulate matter collected from Dunkirk (Northern of France). Among selected relevant metal cations present in its airbone particulate matter, such as Na(+), K(+), Mg(2+), Ca(2+), Al(3+), Cr(3+), Mn(2+) and Zn(2+), this molecular device proved to be outstandingly sensitive toward Fe(3+) with a limit of detection of 1.49 ppb (2.1×10(-8) M) in methanol allowing the estimation of total iron in atmospheric particles.

Potential New Inhibitors of Growth Factors Via the Coupling Between an Hydroxybisphosphonic Acid and an Oligonucleotide

Recent studies have shown that antisens phosphorothioate oligodeoxynucleotide did not allow the VEGF/VPF (vascular endothelial growth factor, vascular permeability factor) expression in normal epidermal keratinocytes. We suggest to compare the biological activity of an oligonucleotide bound to a hydroxybisphosphonic acid via an aminolink to the phosphorothioate oligonucleotide. We report here the synthesis of this compound. After obtaining the carboxylic function, methyl esters of 2 were transesterified by 4,2 eq of bromotrimethylsilane. Compound 3 which is very sensitive to hydrolysis was reacted with