A new generation of aprotic yet Brønsted acidic imidazolium salts: effect of ester/amide groups in the C-2, C-4 and C-5 on antimicrobial toxicity and biodegradation

Gore, Rohitkumar G.; Myles, Lauren; Špulák, Marcel; Beadham, Ian; Garcı́a, M. Teresa; Connon, Stephen J.; Gathergood, Nicholas

doi:10.1039/c3gc40992a

Cited by 48 publications

(48 citation statements)

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“…9. 51 Alkyl substituted imidazolium (8,13), pyridinium (16,17) and dimethylamino-pyridinum (18-20) ILs were not found to be readily anaerobically biodegradable compounds under the studies test conditions (Table 9). Attempts to induce biodegradation by co-metabolism through the addition of an acetate salt failed.…”

Section: Biodegradation Of Ils Under Denitrifying Conditionsmentioning

confidence: 97%

“…Low biodegradation (5-10%) for the C4 substituted analogues (84,85), Fig. 17 Thus the more stable to hydrolysis amide group was examined to investigate the effect of a stable EWG on the imidazolium ring to promote breakdown. There is no evidence that the introduction of an ester group to the imidazolium ring leads to breakdown of the charged heterocycle.…”

Section: View Article Onlinementioning

confidence: 99%

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Biodegradation of ionic liquids – a critical review

2015

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The importance of biodegradation data as part of the design of safer chemicals is presented using ionic liquids (ILs) as a model study. Structural features that promote/impede IL biodegradation, IL design strategies, methods of biodegradation analysis, properties of IL/surfactant derivatives and computational methods of predicting biodegradation are discussed. The importance of metabolite studies as part of biodegradation assays is highlighted. The relevance of applying the lessons learned developing biodegradable ILs to other chemical classes is proposed. A comprehensive appendix of IL biodegradation data published since 2010 (∼300 ILs) has been compiled.

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Section: Biodegradation Of Ils Under Denitrifying Conditionsmentioning

confidence: 97%

Section: View Article Onlinementioning

confidence: 99%

Biodegradation of ionic liquids – a critical review

2015

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“…In 2013, Gathergood and Connon published a combined microbial toxicity, biodegradation, green chemistry metrics and catalyst performance study of a series of ILs. [31][32][33] One of the findings from this work was that the ILs studied containing amide group(s) exhibited very low biodegradation in the CO 2 Headspace test. This was in agreement with previous results for amide containing ILs, [33][34][35] with an exception being 2 and 3 reported by Gathergood in 2012, (Fig.…”

Section: Introductionmentioning

confidence: 92%

Synthesis of a series of amino acid derived ionic liquids and tertiary amines: green chemistry metrics including microbial toxicity and preliminary biodegradation data analysis

Jordan

Haiß

Špulák³

et al. 2016

Green Chem.

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A series of L-phenylalanine ionic liquids (ILs), L-tyrosine ILs, tertiary amino analogues and proposed transformation products (PTPs) have been synthesised. Antimicrobial toxicity data, as part of the green chemistry metrics evaluation and to supplement preliminary biodegradation studies, was determined for ILs, tertiary amino analogues and PTPs. Good to very good overall yields (76 to 87%) for the synthesis of 6 ILs from L-phenylalanine were achieved. A C 2 -symmetric IL was prepared from TMS-imidazole in a one-pot two-step method in excellent yield (91%). Synthesis of the L-tyrosine IL derivatives utilised a simple protection group strategy by using an extra equivalent of the bromoacetyl bromide reagent. Improvements in the synthesis of the α-bromoamide alkylating reagent from L-phenylalanine were achieved, directed by green chemistry metric analysis. A solvent switch from dichloromethane to THF is described, however the yield was 15% lower. Antimicrobial activity testing of L-phenylalanine ILs, L-tyrosine ILs, tertiary amino analogues and PTPs, against 8 bacteria and 12 fungi strains, showed that no compound had a high antimicrobial activity, apart from an L-proline analogue. In this exceptional case, the highest toxicity (IC 95 = 125 and 250 µM) was observed towards the two Gram positive strains Staphylococcus aureus and Staphylococcus epidermidis respectively. High antimicrobial activity was not found for the other bacteria or fungi strains screened. The limitations of the antimicrobial activity study is discussed in relation to SAR studies. Preliminary analysis of biodegradation data (Closed Bottle Test, OECD 301D) is presented. The pyridinium IL derivative is the preferred green IL of the series based on synthesis, toxicity and biodegradation considerations. This work is a joint study with Kümmerer and co-workers and the PTPs were selected as target compounds based on concurrent biodegradation studies by the Kümmerer group. For the comprehensive biodegradation and transformation product analysis see the accompanying paper.

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“…Commonly studied ILs are comprised of bulky, N-containing organic cations (e.g., imidazole and pyridine) in combination with anions, ranging from simple inorganic ions (e.g., halides) to more complex organic species (e.g., sugars and amino acids). 12,14,15 Cytotoxicity is the property of a compound that can result in a toxic effect against human cells, and this effect has been broadly reported for monocationic ILs. 13 Although ILs have been proposed as new "green strategy", problems associated with cytotoxicity and environmental contamination have been reported.…”

Section: Introductionmentioning

confidence: 99%

“…16 Anionic moieties have been discussed to also play an important role in toxicity, however to a lesser extent in comparison to cations. 1,15,[24][25][26][27][28] The introduction of longer alkyl chains on the imidazolium cation generally results in potent activity, which consequently lowers the minimal inhibitory concentration (MIC) against microorganisms. 20,21 Considering these ndings, we hypothesize that introducing a new cationic moiety in the imidazolium cation can reduce the toxicity of ILs due to an increase in polarity of the IL structure.…”

Section: Introductionmentioning

confidence: 99%

Dicationic imidazolium-based ionic liquids: a new strategy for non-toxic and antimicrobial materials

et al. 2014

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New dicationic imidazolium-based ionic liquids (ILs) were synthesized, characterized and tested in regards to cytotoxicity and antimicrobial activity. Insertion of a new cationic head and use of organic anions increased the biocompatibility of the ILs developed. IC 50 (concentration necessary to inhibit 50% of enzymatic activity) values obtained were considerably higher than those described for monocationic ILs, which indicates an improvement in cytocompatibility. Antimicrobial activity against bacterial species of clinical relevance in wounds and the oral environment was tested. The results showed that ILs were effective in inhibiting bacterial growth even below the minimum inhibitory concentration (MIC). It was observed that structural features that confer higher hydrophobicity to ILs decreased both the IC 50 and MIC simultaneously. However, it was possible to establish an equilibrium between those two effects, which gives the safe range of concentrations that ILs can be employed. The results demonstrated that the dicationic-imidazolium-based ILs synthesized may constitute a potent strategy for applications requiring non-toxic materials exhibiting antimicrobial activity.

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A new generation of aprotic yet Brønsted acidic imidazolium salts: effect of ester/amide groups in the C-2, C-4 and C-5 on antimicrobial toxicity and biodegradation

Cited by 48 publications

References 90 publications

Biodegradation of ionic liquids – a critical review

Biodegradation of ionic liquids – a critical review

Synthesis of a series of amino acid derived ionic liquids and tertiary amines: green chemistry metrics including microbial toxicity and preliminary biodegradation data analysis

Dicationic imidazolium-based ionic liquids: a new strategy for non-toxic and antimicrobial materials

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