Some Observations on Cyanic Acid and Cyanates

Lister, M. W.

doi:10.1139/v55-050

Cited by 61 publications

(38 citation statements)

References 5 publications

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“…(2), we extracted E0 = 15.3 kcalꞏmol -1 (0.66 eV) by the least-squares fitting. The obtained E0 is in a good agreement with the literature value of 16 kcalꞏmol -1 (0.69 eV) (24). As the data and Eq.…”

Section: Resultssupporting

confidence: 91%

Cavity Catalysis ‒Accelerating Reactions under Vibrational Strong Coupling‒

Hiura¹,

Shalabney²,

George³

2018

Preprint

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In conventional catalysis the reactants interact with specific sites of the catalyst in such a way that the reaction barrier is lowered and the reaction rate is accelerated. Here we take a radically different approach to catalysis by strongly coupling the vibrations of the reactants to the vacuum electromagnetic field of a cavity. To demonstrate the possibility of such cavity catalysis, we have studied hydrolysis reactions under strong coupling of the OH stretching mode of water to a Fabry-Pérot (FP) microfluidic cavity mode. This results in an exceptionally large Rabi splitting energy ℏΩR of 92 meV (740 cm−1), indicating the system is in vibrational ultra-strong coupling (V-USC) regime and we have found that it enhances the hydrolysis reaction rate of cyanate ions by 102 times and that of ammonia borane by 104 times. This catalytic ability is shown to depend only upon the cavity tuning and the coupling ratio. Given the vital importance of water for life and human activities, we expect our finding not only offers an unconventional way of controlling chemical reactions by ultra-strong light-matter interactions, but also changes the landscape of chemistry in a fundamental way.

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Section: Resultssupporting

confidence: 91%

Cavity Catalysis ‒Accelerating Reactions under Vibrational Strong Coupling‒

Hiura¹,

Shalabney²,

George³

2018

Preprint

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“…Cyanate is relatively stable in alkaline solution (hydrolysis rate of 0.01% h Ϫ1 ) but rapidly decomposes to CO 2 and NH 3 below about pH 4.5 (27). Consequently, unreacted N 14 CO Ϫ was removed from samples by acidification and driving off the resulting 14 CO 2 by evaporation.…”

Section: Methodsmentioning

confidence: 99%

Involvement of the cynABDS Operon and the CO ₂ -Concentrating Mechanism in the Light-Dependent Transport and Metabolism of Cyanate by Cyanobacteria

et al. 2007

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The cyanobacteria Synechococcus elongatus strain PCC7942 and Synechococcus sp. strain UTEX625 decomposed exogenously supplied cyanate (NCO ؊ ) to CO 2 and NH 3 through the action of a cytosolic cyanase which required HCO 3 ؊ as a second substrate. The ability to metabolize NCO ؊ relied on three essential elements: proteins encoded by the cynABDS operon, the biophysical activity of the CO 2 -concentrating mechanism (CCM), and light. (3,28,49). Spontaneous decarboxylation of the carbamate subsequently yields a second CO 2 and NH 3 . Assimilation of cyanate-derived NH 3 and CO 2 then proceeds through conventional metabolic pathways providing a unique source of nitrogen (N) for growth in a variety of bacteria and a source of carbon (C) for autotrophic metabolism (7,15,30,41,50,53).In E. coli, the coexpression of carbonic anhydrase (CA) is vital to maintain ongoing cyanate metabolism (17, 23). Mutants lacking CA activity do not readily catalyze cyanate decomposition, are unable to grow with NCO Ϫ as the sole N source, and are far more susceptible than wild-type cells to the toxic effects of cyanate itself on growth (18,(22)(23)(24). CA involvement is related to the absolute requirement by cyanase for HCO 3 Ϫ (rather than CO 2 ) as a substrate in the reaction. Physiological studies (17,18,22,23) indicate that in the absence of CA, the CO 2 generated from cyanate decomposition diffuses out of cells faster than it can be hydrated nonenzymatically to HCO 3 Ϫ . This leads to a cellular depletion of HCO 3 Ϫ and cessation of cyanate metabolism through substrate deprivation. CA prevents this cellular depletion by trapping CO 2 and catalytically regenerating HCO 3 Ϫ within cells at a rate that is not limiting for cyanase.Carbonic anhydrase, cyanase, and a hydrophobic protein designated as CynX are encoded by cynT, cynS, and cynX (4, 44), respectively, which are arranged in an operon in E. coli, ensuring the coordinated expression of the two enzymes required for cyanate decomposition. Expression of the cynTSX operon is induced by exogenous cyanate and positively regulated by CynR (45), a member of the LysR family of regulatory proteins. The cynR gene is located immediately upstream of the cynTSX operon but is transcribed in the opposite direction.The photoautotrophic cyanobacterium Synechococcus sp. strain UTEX 625 also converts exogenous cyanate to CO 2 and NH 3 as described in the reaction above (30). Inhibitor studies (30) have shown that cyanate-derived NH 3 is rapidly incorporated by this cyanobacterium via the central nitrogen assimilation pathway, and it has recently been suggested that NCO Ϫ can serve as the sole source of N for growth of the globally important marine cyanobacterium Synechococcus sp. strain WH8102 (35,43). CO 2 arising from cyanate decomposition is also rapidly assimilated by Synechococcus sp. strain UTEX 625

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“…Cyanate is known to decompose to ammonium and carbon dioxide in both neutral and slightly acidic aqueous solutions (up to pH 7.8), while temperature and ionic strength affect the decomposition rate constant (Lister 1955). Subsequently, we studied whether cyanate decomposition occurs in seawater (pH 8.2-8.3, ionic strength 0.7 mol L 21 ) with its high inorganic carbon concentrations and significant buffering capacity.…”

Section: Speciesmentioning

confidence: 99%

The cyanate utilization capacity of marine unicellular Cyanobacteria

Kamennaya

Chernihovsky²,

Post

2008

Limnology & Oceanography

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Cyanate, a by-product of urea decomposition, is a potential nitrogen (N) source in marine environments, but to date it has received scant attention. Cyanobacteria presumably acquire this compound via a substrate-specific ABC-type transporter (cynABD), and they convert it to ammonium and carbon dioxide by cyanase (cynS) activity. Participation of cyanate utilization genes in N-stress responses in cyanobacteria has been implied previously, but its ecological context has not been studied. We employed polymerase chain reaction protocols for cynA amplification to examine the potential for cyanate recruitment in the Gulf of Aqaba, northern Red Sea. We also monitored growth of cyanobacterial strains with different cynABDS complements on cyanate-containing media. We showed that cyanate is utilized as the sole N source by strains with the full gene complement, and residual growth, fed by natural decay of cyanate to ammonium, was observed in strains lacking any of these genes. Natural abundance of cynA products in the oligotrophic Gulf of Aqaba indicates that cyanate constitutes an essential N source for Prochlorococcus, but not for Synechococcus populations. Noncyanobacterial cynA sequences indicate cyanate utilization by a variety of other phototrophic microorganisms. We hypothesize that in stratified water bodies, cyanate utilization is confined to the N-deplete upper photic zone, where it plays a role in ''regenerated'' primary production.

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Some Observations on Cyanic Acid and Cyanates

Cited by 61 publications

References 5 publications

Cavity Catalysis ‒Accelerating Reactions under Vibrational Strong Coupling‒

Cavity Catalysis ‒Accelerating Reactions under Vibrational Strong Coupling‒

Involvement of the cynABDS Operon and the CO ₂ -Concentrating Mechanism in the Light-Dependent Transport and Metabolism of Cyanate by Cyanobacteria

The cyanate utilization capacity of marine unicellular Cyanobacteria

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Some Observations on Cyanic Acid and Cyanates

Cited by 61 publications

References 5 publications

Cavity Catalysis ‒Accelerating Reactions under Vibrational Strong Coupling‒

Cavity Catalysis ‒Accelerating Reactions under Vibrational Strong Coupling‒

Involvement of the cynABDS Operon and the CO 2 -Concentrating Mechanism in the Light-Dependent Transport and Metabolism of Cyanate by Cyanobacteria

The cyanate utilization capacity of marine unicellular Cyanobacteria

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Involvement of the cynABDS Operon and the CO ₂ -Concentrating Mechanism in the Light-Dependent Transport and Metabolism of Cyanate by Cyanobacteria