01940nas a2200229   4500008004100000022001400041245005900055210005900114260000800173300001400181490000700195520116800202100003001370700001901400700004801419700002501467700002501492700003201517700003601549700003101585856009401616       2020                        eng d  a0003-270000aGeometrical isomerism directed electrochemical sensing0 aGeometrical isomerism directed electrochemical sensing  cMAR  a4541-45470 v923 a<p>We report the independent role of isomerism of secondary sphere substituents over their nature, a factor often overlooked in molecular electrocatalysis pertaining to electrochemical sensing, by establishing that isomerism redefines the electronic structure at the catalytic reaction center via geometrical factors. UV-vis spectroscopy and X-ray photoelectron spectroscopy suggest that a substituent's isomerism in molecular catalysts conjoins molecular planarity and catalytic activation through competing field effects and resonance effects. As a classical example, we demonstrate the influence of isomerism of the -NO2 substituents for the electrocatalytic multi electron oxidation of As(III), a potentially important electrochemical pathway for water remediation and arsenic detection. The isomerism dependent oxidative activation of catalytic center leads to a nonprecious molecular catalyst capable for direct As(III) oxidation with an experimental detection limit close to WHO guidelines. This work opens up an unusual approach in analytical chemistry for developing various sensing platforms for challenging chemical and electrochemical reactions.</p>
1 aKottaichamy, Alagar, Raja1 aBegum, Shabbah1 aDevendrachari, Mruthyunjayachar, Chattanaha1 aBhat, Zahid, Manzoor1 aThimmappa, Ravikumar1 aKotresh, Harish, Makri Nimb1 aVinod, Chathakudath, Prabhakara1 aThotiyl, Musthafa, Ottakam  uhttps://library.ncl.res.in/content/geometrical-isomerism-directed-electrochemical-sensing02183nas a2200253   4500008004100000022001400041245007600055210006900131260000900200300001200209490000700221520128000228100003001508700001901538700003401557700003201591700004901623700002501672700002501697700003201722700003601754700003101790856010801821       2020                        eng d  a1948-718500aUnprecedented isomerism-activity relation in molecular electrocatalysis0 aUnprecedented isomerismactivity relation in molecular electrocat  cJAN   a263-2710 v113 a<p>The role of electrocatalysts in energy storage/conversion, biomedical and environmental sectors, green chemistry, and much more has generated enormous interest in comprehending their structure-activity relations. While targeting the surface-to-volume ratio, exposing reactive crystal planes and interfacial modifications are time-tested considerations for activating metallic catalysts; it is primarily by substitution in molecular electrocatalysts. This account draws the distinction between a substituent's chemical identity and isomerism, when regioisomerism of the -NO2 substituent is conferred at the ``alpha'' and ``beta'' positions on the macrocycle of cobalt phthalocyanines. Spectroscopic analysis and theoretical calculations establish that the beta isomer accumulates catalytically active intermediates via a cumulative influence of inductive and resonance effects. However, the field effect in the alpha isomer restricts this activation due to a vanishing resonance effect. The demonstration of the distinct role of isomerism in substituted molecular electrocatalysts for reactions ranging from energy conversion to biosensing highlights that isomerism of the substituents makes an independent contribution to electrocatalysis over its chemical identity.</p>
1 aKottaichamy, Alagar, Raja1 aBegum, Shabbah1 aNazrulla, Mohammed, Azeezulla1 aDargily, Neethu, Christudas1 aDevendrachari, Mruthyunjayachari, Chattanaha1 aBhat, Zahid, Manzoor1 aThimmappa, Ravikumar1 aKotresh, Harish, Makri Nimb1 aVinod, Chathakudath, Prabhakara1 aThotiyl, Musthafa, Ottakam  uhttps://library.ncl.res.in/content/unprecedented-isomerism-activity-relation-molecular-electrocatalysis