research article electrochemical studies of betti base and...

Hindawi Publishing CorporationInternational Journal of ElectrochemistryVolume 2013 Article ID 678013 9 pageshttpdxdoiorg1011552013678013

Research ArticleElectrochemical Studies of Betti Base and Its Copper(II)Complex by Cyclic and Elimination Voltammetry

Shardul Bhatt and Bhavna Trivedi

Department of Chemistry Faculty of Science The MS University of Baroda Vadodara 390 002 India

Correspondence should be addressed to Bhavna Trivedi trivedibhavnayahoocom

Received 30 September 2013 Accepted 3 November 2013

Academic Editor Shengshui Hu

Copyright copy 2013 S Bhatt and B Trivedi This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The electrochemical behavior of Betti base 1-(120572-amino benzyl)-2-naphthol (BB) and its copper(II) complex by cyclic and eliminationvoltammetry (EVLS) is reported in the present study The cyclic voltammetric studies carried out at a glassy carbon workingelectrode AgAg+ reference electrode (001M AgNO

3in acetonitrile) in DCM at 100mVsec 200mVsec and 400mVsec scan

rates indicated a preceding chemical oxidation of the adsorbed BB species to form an iminium ion followed by formation ofa carbanion via two-step quasireversible reduction The suggested reaction mechanism has been supported by the eliminationvoltammetry The CV and EVLS studies revealed Cu(II)BB complex to undergo a chemical or a surface reaction before electrontransfer from the electrode at minus049 V to formCu(I)BB speciesThe oxidation of Cu(I)BB species has been observed to be CV silent

1 Introduction

The study of chemistry of Betti base (Figure 1) started in thebeginning of the 20th century when Betti reported the syn-thesis of 1-(120572-amino benzyl)-2-naphthol (Betti base BB) [1]

BB and its derivatives have been extensively used as aux-iliary in catalytic reactions particularly in addition of dieth-ylzinc to arylaldehyde [2] and various coupling reactions likeMizoroki-Heck Suzuki-Miyaura and Sonogashira [3] It issuggested that the role of auxiliary amino ligands in Pd cata-lyzed reactions is to stabilize the catalytically active Pd(0) spe-cies [4]This observation calls for an exhaustive investigationof the redox property of the ligand BB with ndashNH

2and ndash

OH groups at 1 and 3 positions respectively is expected toact as an excellent ligand for coordination with transitionmetal ions and Cu(II) complex with BB has been reported[5] BB with sp3 hybridized carbon attached to phenyl ringamine and naphthol is expected to exhibit an interestingredox property

Cyclic voltammetry is an excellent technique to probechemical changes that occur as a result of electron transferOne of the strengths of the CV technique is in the identifica-tion of electrochemical reactions involving combinations ofelectron transfer and chemical reaction steps through proper

analysis of CV curves recorded at various scan rates Manymathematical models have been proposed to extract usefulinformation from theCVdata [6] and elimination voltamme-try is one such model Elimination voltammetry with linearscan (EVLS) an electrochemical method comprising theelimination of some particular currents from the measure-ments of linear scan voltammetry was first proposed byDracka and simultaneously verified by Trnkova in 1996 [7 8]A large volume of work has been published by Trnkova et al[8ndash15]Most of these papers point to EVLS as an excellent toolto understand electrochemical processes It is successfullyemployed in the analysis of nucleic acids and short homo- orheterodeoxyoligonucleotides (ODNs) containing adenine(A) and cytosine (C) [15ndash17]

The simplicity and sensitivity of the elimination tool pro-mpted us to explore its application to study electrochemicalbehavior of BB and its Cu(II) complex

2 Theory

The EVLS can be considered as a transformation of current-potential curves capable of eliminating some selected currentcomponents while conserving others by means of elimina-tion functions [7 18]

2 International Journal of Electrochemistry

OH

NH2

1-(120572-Amino benzyl)-2-naphthol

Figure 1 Betti base (BB)

The elimination function is based on rate dependence ofvarious currents that is diffusion current kinetic currentcharging current and so forth Let 119868 be the total reference cur-rent measured at reference scan rate ]ref and 11986812 and 1198682 thetotal currents measured at scan rates equal to one-half andtwice of the reference current scan rate ]ref respectively Thetotal currents recorded at the scan rates (12)]ref ]ref and2]ref can be given as

11986812= (119868119889)12+ (119868119888)12+ (119868119896)12

119868 = (119868119889) + (119868119888) + (119868119896)

1198682= (119868119889)2+ (119868119888)2+ (119868119896)2

(1)

Elimination is produced by the construction of a function ofthe total current 119891(119868) in the form of a linear combination oftotal currents measured at different scan rates and can be ex-pressed as

119891 (119868) = 119886111986812+ 1198862119868 + 11988631198682 (2)

With respect to nature of the simple currents shown only theratio of scan rate ] to the reference scan rate ]ref is importantThe total currents used in linear combination are thenmarkedwith an index expressing ]]ref ratios so 1198682 is the totalcurrent for ]]ref = 2 and so forth and can be expressed as

119886111986812= 1198861(

1

2

)

12

(119868119889) + 1198861(

1

2

) (119868119888) + 1198861(119868119896)

1198862119868 = 1198862(119868119889) + 1198862(119868119888) + 1198862(119868119896)

11988631198682= 1198863(2)12

(119868119889) + 1198863(2) (119868119888) + 1198863(119868119896)

(3)

For the conservation of diffusion current with simultaneouselimination of kinetic and charging currents the followingrequirements should be fulfilled

1198861(

1

2

)

12

(119868119889) + 1198862(119868119889) + 1198863(2)12

(119868119889) = 119868119889

1198861(

1

2

) (119868119888) + 1198862(119868119888) + 1198863(2) (119868119888) = 0

1198861(119868119896) + 1198862(119868119896) + 1198863(119868119896) = 0

(4)

The coefficients 1198861 1198862 and 119886

3can be obtained by solving the

above three equations simultaneously using Matlab program[9 19] and their values are calculated as

1198861= minus11657 119886

2= 17485 119886

3= minus58284 (5)

Hence the elimination function for conservation of diffusioncurrent with simultaneous elimination of kinetic and charg-ing current can be given as E4 [7] simultaneous eliminationof 119868119896and 119868119888 with conservation of 119868

119889

119891 (119868) = minus1165711986812+ 17485119868 minus 58284119868

2 (6)

As a result of elimination the reversible current of a substancetransported to an electrode surface by diffusion only is im-proved giving sharp peaks for reduction or oxidation signalsFor the irreversible current of a fully adsorbed substance thisfunction provides the characteristic signal of a peak-to-coun-terpeak form improving strongly the resolution and sensitiv-ity [7 14 15 18 20 21]Thus for the application of eliminationvoltammetry all that is needed is voltammetric data at threescan rates Once this data is fed into an appropriate elim-ination equation in MS Excel program it generates infor-mation that is useful for understanding the electrochemicalprocesses

International Journal of Electrochemistry 3

20

10

00

minus10

minus20

minus09 minus06 minus03 060300

I(120583

A)

V volts versus AgAg+

(a)

00

05minus10 minus05 1510

200

150

100

50

minus50

a1

a2

c1c2

00

I(120583

A)


(b)

00 05minus10 minus05 1510

00

200

150

100

50

minus50

minus100

a1

a2

c1

c2

I(120583

A)


(c)

Figure 2 Cyclic voltammograms of Betti base (1mM in DCM)using 01M tetra-n-butylammonium hexafluorophosphate as thesupporting electrolyte (a) 05 V to minus09V (b) 12 V to minus09V and(c) 00 V to minus09V

000

1300

2600

3900

5200

minus2600

minus1300


a1

a2

c1

c2

I(120583

A)


Figure 3 Cyclic voltammogram of the Betti base at increasing scanrate from 100 to 500mVsec

3 Experimental

31 Chemicals BB was synthesized by the reported method[1] Formation of BB was confirmed by elemental analysisFTIR 1H NMR and 13C NMR spectroscopy

32 Characterization of BB MP 122ndash124∘C reported MP124∘C

Anal Calc for C17H15NO (24931) C 818 H 601 N 56

Found C 8143 H 602 N 5551HNMR (CDCl

3) d 767ndash770 (m 3H) 713ndash742 (m 8H)

610 (s 1H) 239 (br s 2H)13C NMR (CDCl

3) d 1569 1424 1320 1297 1290

1287(2C) 1285 1279 1273(2C) 1264 1224 1212 1205 1151559

IR (KBr cmminus1) 3384 3297 3029 1622 1599 1469 1452UV (nm) 292 (120576 sim 3500) b 337 (120576 sim 2900)All chemicals usedwere of AR grade Freshly distilled sol-

vents were employed for all synthetic purposes

33 Synthesis of Cu(II)BB Complex The Cu(II)BB complexwas prepared by mixing 2mM solution of ligand in methanolwith 1mM solution of CuCl

2sdot 2H2OThemixture was stirred

for 30min at room temperatureThe solid separated from thesolution was collected on a Whatman filter paper washedwith small amount of methanol and dried under vacuumThe purity of the isolated complex was confirmed by TLC(hexane ethyl acetate 5 1) No unreacted ligand was foundFurther the complex was characterized by various spectraltechniques like FT-IR UV-Vis elemental analysis EPR FAB-mass and single crystal XRD [5]

34 Voltammetric Measurements Electrochemical measure-ments were performed on a CH Instruments 600C potentio-stat with a glassy carbon as working electrode (area0071 cm2) AgAg+ reference electrode (001M AgNO

3in

acetonitrile caution keep vycor frit of reference electrodewet


00

200

400

600

At natural pH (8-9)At high pH (11-12)At low pH (3-4)

05minus10minus15 minus05 1510

minus200

minus400

minus600

00

a1

a2

c1

c2

I(120583

A)


Figure 4 Cyclic voltammograms of a 1mM solution of BB inDCM at 300mVsec containing 01M tetra-n-butylammoniumhexafluorophosphate as the supporting electrolyte

to prevent the leakage of AgNO3solution and frequently

change the filled solution) and Pt wire as a counter electrodeTo obtain reproducible results the glassy carbon electrodewas polished using polishing kit (CHI120) which consisted ofa polishing polyurethane pad alpha Al

2O3(particle size 10

and 03 120583m) and gamma Al2O3powder (particle size 005

120583m)The electrode was polished with 005120583m alumina soni-cated (ultrasound bath) for 3min and finally rinsed withdeionized water before each measurement Cyclic voltam-metric studies were carried out using dichloromethane solu-tion of BB and Cu(II)BB (10mM) taking tetra-n-butylammonium hexafluorophosphate (01M) as the supportingelectrolyte Solutions were deoxygenated by bubbling drynitrogen prior to the potential sweep All experiments werecarried out at room temperature

35 Data Treatment The voltammetric data was collectedusing CH600C Potentiostat instrument and exported to MSExcel for processing of elimination functions The elimina-tion function 119891(119868

119889) has been selected for the evaluation of

measurement

119891 (119868119889) = minus 11657 times 119868

12+ 17485 times 119868 minus 58284 times 119868

2 (7)

4 Results and Discussion

41 Cyclic Voltammetry of BB The cyclic voltammograms ofBB (10mM 100mVsec) in the potential window of (A) 05 Vto minus09V (B) 12 V to minus09V and (C) 00V to minus09V followedby reverse scan from minus09V to 12 V and finally second cyclefrom 12 V to minus09V are given in Figures 2(a) 2(b) and 2(c)

No significant electrochemical activity is observed in thepotential range of 05 V to minus09V (Figure 2(a))The CV of BB

00

200

400

600

800

E4 oxidationCV oxidation

minus200


a2IP

a2ICPPrepeak

00

a1


a9984001

f(Id)

(120583A

)

(a)

00

100

200

300

400

E4 reduction CV reduction

minus100


V (volts versus AgAg+)

c3IPc1

c2

f(Id)

(120583A

)

ICP

(b)

Figure 5 Plots for diffusion current 119868119889for BB (a) oxidation process

and (b) reduction process

exhibited two cathodic and two anodic peaks when scannedfrom 12V tominus09V and back to 12 V (Figure 2(b)) Howeveras shown in Figure 2(c) no cathodic peak is observed whenit is scanned from 00V to minus09V an anodic peak at 068Vappears on reversal of scan direction from minus09V to 12 VFinally in the second cycle of CV from 12 V to minus09V andback to 12 V it exhibited two cathodic (c1 at minus02 V and c2 atminus08V) and two anodic peaks (a1 at 068V and a2 at 017 V)The cyclic voltammograms recorded at various scan rates(100mVsec to 500mVsec) are shown in Figure 3 It reveals asmall shift in peak potentials and increase in peak height withincrease in scan rate

CVs recorded at three different pH conditions are shownin Figure 4


00

500

1000

E4 oxidation at low pHCV oxidation


Prepeakminus500

minus1000

a1

a2

00

a9984001f(Id)

(120583A

)


(a)

00

400

800

1200

E4 oxidation at high pHCV oxidation


a1

a2

f(Id)

(120583A

)


(b)

00

500

1000

Low pHNatural pHHigh pH

Prepeaksminus500

minus1000

a2

a1

a9984001

00 05minus10minus15 minus05 1510

f(Id)

(120583A

)


(c)

Figure 6 Plots for diffusion current 119868119889for BB (a) oxidation process at low pH (b) oxidation process at high pH and (c) overlay plot for

oxidation process

Figure 4 exhibits small changes in the peak potential val-ues for the oxidation processes a1 and a2 and reduction proc-ess c2 however the c1 reduction peak potential appears to beunaffected by the change in pH

Identification of the nature of currents involved in theelectron transfer process that is diffusion kinetic or adsorp-tive would augment the understanding of the process and asdiscussed above the elimination voltammetry is the mostappropriate tool for the purpose [12]

The elimination function which eliminates simultane-ously charged and kinetic currents and conserves diffusioncurrent [14]

Equation (7) was applied to the CV data obtained at threescan rates 100 200 and 400mVsec considering 200mVsec

as reference scan rate For the sake of simplicity the overlaycurves of elimination function 119891(119868

119889) and CV for the forward

and reverse scans are displayed separately (Figures 5(a) and5(b))

The elimination procedure resulted in a peak-counterpeak (a2) and a prepeak-peak (a

1015840

1 and a1) (Figure 5(a)) Theelimination function applied to the data for the reversed scansof CV resulted in two peaks c1 with no change in peak heightand c2 with a small increase in peak height (Figure 5(b))Apart from these two peaks application of the119891(119868

119889) function

resulted in a small peak-counter peak at c3 (Figure 5(b))To understand the effect of pH on elimination function

the CV data were collected at three different scan rates 100200 and 400mVsec for each three pH conditions namely


OH

H

(I)

NH

OH OH

(II) (III)

H

H

N

OHH

H

(IV)

N

OHH

H

(V)

N H

H

(VI)

H

(VII)

H

∙ ∙ ∙ ∙

∙

∙

NH2

NH2

minus2H+

H+

Ominus

Ominus

minus2eminus

+eminus

+eminus

minuseminus

+

N+

Scheme 1 Proposed mechanism for the redox reaction of BB

acidic basic and naturalThe resulting elimination curves foranodic process are given in Figure 6

On the basis of CV and elimination function data the fol-lowing mechanism is proposed (Scheme 1)

The dependence of the overall redox process on the highpositive values of the initial potential 12 V (Figure 2(c)) indi-cates a need of overpotential to increase the charge transferfor the formation of a species II (a1) as the first step at068VThis step might be controlled by either mass transportdiffusion processes or a preceding chemical reaction associ-ated with the charge transfer reaction giving kinetic currentor may be a combination of both The appearance of the pre-peak a

1015840

1 (Figure 5(a)) in the elimination curve may be due toproton transfer followed by electron transfer This is furtherconfirmed by the pH dependence of peak a1 in the CV(Figure 4) and prepeak a

1015840

1 in the EVLS curves (Figures 6(a)and 6(c)) The decrease in prepeak currents with the increasein pH (Figure 6(c)) indicates decreased tendency of protontransfer prior to the electron transfer A complete disappear-ance of the prepeak and increased height of the peak a1 atalkaline pH in the EVLS (Figure 6(b)) hint towards a pos-sibility of simultaneous transfer of proton and electron Thespecies II is in equilibrium with a protonated iminium ionIIIwhich undergoes reduction at minus024V (c1 Figure 2(b)) toform a radical IV The radical IV is further reduced to forma benzylic carbanion V (c2 Figure 2(b)) The benzylic anionwould be expected to quickly equilibrate to the phenoxideThis step is pH dependent A similar electrochemical study ofproton coupled electron transfer mechanism has been re-viewed by Costentin et al [22] The final step is the oxidationof VI at 017 V (a2) to give an amine cation radical VII

As exhibited in Figure 4 the oxidation of VI to VII is pHdependent step The EVLS curve obtained on application of119891(119868119889) (Figure 5(a)) exhibits increased height of a2 indicating

a quasi-reversible diffusion controlled process [14]

42 The Electrochemical Study of Cu(II)BB The ORTEP dia-gram of Cu(II)BB as reported [5] is given as inset in Scheme 2for the reference As can be seen from the diagram the copperatom is bonded to two-nitrogen and two-oxygen atoms bothpairs are in trans position with a perfect square planer geo-metry around copper

The cyclic voltammogram for the isolated complexCu(II)BB as shown in Figure 7(a) exhibited an anodic peak at033V followed by a cathodic peak atminus049VThe eliminationfunction E4 (7) applied to the CVdata collected at three scan-ning rates 100 200 and 400mVsec [7 8 16 18] for the oxi-dation process resulted in a prepeak (1199091015840) and peak-counterpeak (119909) (11990910158401015840) as depicted in Figure 7(c) The application ofelimination function E4 resulted in a prepeak-peak c

1015840

1 and c1as shown in Figure 7(d)

On the basis of the above observations a redox mecha-nism for Cu(II)BB has been proposed as Scheme 2

The oxidation of the adsorbed ligand is the first step asindicated by the appearance of prepeak-peak at 025V in theEVLS (inset Figure 7(c)) This observation is similar to theoxidation of the ligand with potential values shifted to lesspositive values as expected due to the charge transfer from theligand on coordination to the metal ion This is followed byreduction of the metal ion from Cu(II) to Cu(I) at c1 whichappears as prepeak-peak in EVLS (Figure 7(d)) The appear-ance of prepeak indicates a chemical or a surface reaction


00

200

400a1

c1minus400

minus200

minus06 minus03 00 03

I(120583

A)


(a)

00

100

c1minus400

minus100

minus200

minus300

I(120583

A)

minus06 minus04 minus02 00 02


(b)

00

00

00

100

200 00Prepeak

minus200

minus100

minus06

minus06

minus04

minus03 03

minus02 02

x

x998400

x998400998400

minus200120583

200120583

IP

ICP

f(Id) of Cu(II)BB (oxidation)CV of Cu(II)BB (oxidation)

I(120583

A)


(c)

Prepeak

00

00

minus06minus03 03

minus200120583

200120583

c1

00

400

200

minus200

I(120583

A)

00minus06 minus04 minus02 02

f(Id) of Cu(II)BB (reduction)CV of Cu(II)BB (reduction)


c9984001

(d)

Figure 7 (a) and (b) cyclic voltammogram of Cu(II)BB with increasing scan rate 100mVsec to 400mVsec (c) 119891(119868119889) elimination plot for

the oxidation of Cu(II) complex and (d) 119891(119868119889) elimination plot for the reduction of Cu(II) complex

before electron transfer As can be seen from the voltammo-gram (Figure 7(b)) the peak corresponding to oxidation ofcopper is not observed This could be due to intramolecularelectron transfer via valence tautomerism between electroac-tive ligand and metal ion [23ndash26] causing fast disproportion-ation of Cu(I) complex to give Cu(II) or some rearrangementwithin complex so as to give a more stabilized speciesHowever the EVLS curves (Figure 7(c)) exhibits prepeak-peak at 1199091015840 and 119909 followed by a counterpeak indicating somechemical or a surface reaction prior to diffusion of the speciesin the adsorbed state [18] With the help of CV and EVLS itcan be proved that the Cu(II)BB complex follows CECmechanism

5 Conclusion

This is the first paper where the EVLS technique is applied tostudy the electrochemical behavior of a metal complex EVLShas been found to be the best tool to understand the CV silentchemical processes It can be concluded from the CV andEVLS data that the BB follows CEE where as Cu(II)BB com-plex follows CEC mechanism The electrochemical study ofBB can be useful to enlarge the range of functionality of thederivatives of Betti bases for the organic synthesis FT-IR 1HNMR and 13C NMR spectra of Betti base are given as sup-porting information in Supplementary Material availableonline at httpdxdoiorg1011552013678013


HN

NO

OCu2+

03V H2

H2

HN

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

+H+

minus049V

Scheme 2 Proposed mechanism for the redox reaction of Cu(II)BB

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

Mr Shardul Bhatt is thankful to University Grant Com-mission (UGC F33-2542007 28-2-2008(SR)) and CSIR(09114(0192)2013EMR-I)NewDelhi for financial supportThe authors are thankful to theHeadChemistry DepartmentThe MS University of Baroda for providing the infrastruc-tural facilities

References

[1] M Betti ldquoSynthesis of Betti baserdquo Organic Syntheses Collectivevol 1 pp 381ndash383 1941

[2] C Cimarelli G Palmieri and E Volpini ldquoA practical stereose-lective synthesis of secondary and tertiary aminonaphthols chi-ral ligands for enantioselective catalysts in the addition of dieth-ylzinc to benzaldehyderdquo Tetrahedron Asymmetry vol 13 no 22pp 2417ndash2426 2002

[3] A R Chaudhary andA V Bedekar ldquoSunlight promoted pallad-ium catalyzed Mizoroki-Heck Suzuki-Miyaura and Sonogash-ira reactionsrdquo Tetrahedron Letters vol 53 pp 6100ndash6103 2012

[4] B Tao and D W Boykin ldquoSimple aminePd(OAc)2-catalyzed

Suzuki coupling reactions of aryl bromides under mild aerobic

conditionsrdquo Journal of Organic Chemistry vol 69 no 13 pp4330ndash4335 2004

[5] S Bhatt and B Trivedi ldquoSynthesis and characterization of somenovel copper(II) complexes with an optically active Betti baserdquoPolyhedron vol 35 no 1 pp 15ndash22 2012

[6] A J Bard and L R Faulkner Electrochemical Methods Funda-mentals and Applications John Wiley amp Sons New York NYUSA 1980

[7] O Dracka ldquoTheory of current elimination in linear scan vol-tammetryrdquo Journal of Electroanalytical Chemistry vol 402 no1-2 pp 19ndash28 1996

[8] L Trnkova and O Dracka ldquoElimination voltammetry Experi-mental verification and extension of theoretical resultsrdquo Journalof Electroanalytical Chemistry vol 413 no 1-2 pp 123ndash129 1996

[9] N Serrano A Alberich and L Trnkova ldquoOxidation of 6-ben-zylaminopurine-copper(I) complex on pencil graphite elec-troderdquo Electroanalysis vol 24 no 4 pp 955ndash960 2012

[10] L Trnkova L Zerzankova F Dycka R Mikelova and F JelenldquoStudy of copper and purine-copper complexes on modifiedcarbon electrodes by cyclic and elimination voltammetryrdquo Sen-sors vol 8 no 1 pp 429ndash444 2008

[11] M Supicova R Rozik L Trnkova R Orinakova and MGalova ldquoInfluence of boric acid on the electrochemical deposi-tion of Nirdquo Journal of Solid State Electrochemistry vol 10 no 2pp 61ndash68 2006

[12] L Trnkova I Postbieglova andMHolik ldquoElectroanalytical de-termination of d(GCGAAGC) hairpinrdquo Bioelectrochemistryvol 63 no 1-2 pp 25ndash30 2004


[13] L Trnkova ldquoElectrochemical behavior of DNA at a silver elec-trode studied by cyclic and elimination voltammetryrdquo Talantavol 56 no 5 pp 887ndash894 2002

[14] L Trnkova R Kizek V Adam T Eckschlager and J HubalekSensing in Electroanalysis vol 5 University Press Centre Par-dubice Czech Republic 2010

[15] L Trnkova F Jelen and I Postbieglova ldquoApplication of elimina-tion voltammetry to the resolution of adenine and cytosine sig-nals in oligonucleotides II Hetero-oligodeoxynucleotides withdifferent sequences of adenine and cytosine nucleotidesrdquo Elec-troanalysis vol 18 no 7 pp 662ndash669 2006

[16] L Trnkova F Jelen and I Postbieglova ldquoApplication of elimina-tion voltammetry to the resolution of adenine and cytosine sig-nals in oligonucleotides I Homo-oligodeoxynucleotides dA 9and dC9rdquo Electroanalysis vol 15 no 19 pp 1529ndash1535 2003

[17] L Trnkova F Jelen J Petrlova V Adam D Potesil and RKizek ldquoElimination voltammetry with linear scan as a new de-tection method for DNA sensorsrdquo Sensors vol 5 no 6-10 pp448ndash464 2005

[18] L Trnkova ldquoIdentification of current nature by elimination vol-tammetry with linear scanrdquo Journal of Electroanalytical Chem-istry vol 582 no 1-2 pp 258ndash266 2005

[19] Matlab Version 730267 Mathworks Inc Natick Mass USA2006

[20] F Jelen A Kourilova S Hason R Kizek and L Trnkova ldquoVol-tammetric study of adenine complex with copper on mercuryelectroderdquo Electroanalysis vol 21 no 3-5 pp 439ndash444 2009

[21] N Aladag L Trnkova A Kourilova M Ozsoz and F JelenldquoVoltammetric study of aminopurines on pencil graphite elec-trode in the presence of copper ionsrdquo Electroanalysis vol 22 no15 pp 1675ndash1681 2010

[22] C Costentin M Robert and J-M Saveant ldquoUpdate 1 of elec-trochemical approach to the mechanistic study of proton-cou-pled electron transferrdquo Chemical Reviews vol 110 no 12 ppPR1ndashPR40 2010

[23] E Evangelio and D Ruiz-Molina ldquoValence tautomerism moreactors than just electroactive ligands and metal ionsrdquo ComptesRendus Chimie vol 11 no 10 pp 1137ndash1154 2008

[24] E Evangelio and D Ruiz-Molina ldquoValence tautomerism newchallenges for electroactive ligandsrdquo European Journal of Inor-ganic Chemistry no 15 pp 2957ndash2971 2005

[25] O Rotthaus FThomas O Jarjayes C Philouze E Saint-Amanand J-L Pierre ldquoValence tautomerism in octahedral andsquare-planar phenoxyl-nickel(II) complexes are imino nitro-gen atoms good friendsrdquo Chemistry A European Journal vol12 no 26 pp 6953ndash6962 2006

[26] W Kaim and B Schwederski ldquoCooperation of metals with elec-troactive ligands of biochemical relevance beyond metallopor-phyrinsrdquo Pure andApplied Chemistry vol 76 no 2 pp 351ndash3642004

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Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


OH

NH2

1-(120572-Amino benzyl)-2-naphthol

Figure 1 Betti base (BB)

The elimination function is based on rate dependence ofvarious currents that is diffusion current kinetic currentcharging current and so forth Let 119868 be the total reference cur-rent measured at reference scan rate ]ref and 11986812 and 1198682 thetotal currents measured at scan rates equal to one-half andtwice of the reference current scan rate ]ref respectively Thetotal currents recorded at the scan rates (12)]ref ]ref and2]ref can be given as

11986812= (119868119889)12+ (119868119888)12+ (119868119896)12

119868 = (119868119889) + (119868119888) + (119868119896)

1198682= (119868119889)2+ (119868119888)2+ (119868119896)2

(1)

Elimination is produced by the construction of a function ofthe total current 119891(119868) in the form of a linear combination oftotal currents measured at different scan rates and can be ex-pressed as

119891 (119868) = 119886111986812+ 1198862119868 + 11988631198682 (2)

With respect to nature of the simple currents shown only theratio of scan rate ] to the reference scan rate ]ref is importantThe total currents used in linear combination are thenmarkedwith an index expressing ]]ref ratios so 1198682 is the totalcurrent for ]]ref = 2 and so forth and can be expressed as

119886111986812= 1198861(

1

2

)

12

(119868119889) + 1198861(

1

2

) (119868119888) + 1198861(119868119896)

1198862119868 = 1198862(119868119889) + 1198862(119868119888) + 1198862(119868119896)

11988631198682= 1198863(2)12

(119868119889) + 1198863(2) (119868119888) + 1198863(119868119896)

(3)

For the conservation of diffusion current with simultaneouselimination of kinetic and charging currents the followingrequirements should be fulfilled

1198861(

1

2

)

12

(119868119889) + 1198862(119868119889) + 1198863(2)12

(119868119889) = 119868119889

1198861(

1

2

) (119868119888) + 1198862(119868119888) + 1198863(2) (119868119888) = 0

1198861(119868119896) + 1198862(119868119896) + 1198863(119868119896) = 0

(4)

The coefficients 1198861 1198862 and 119886

3can be obtained by solving the

above three equations simultaneously using Matlab program[9 19] and their values are calculated as

1198861= minus11657 119886

2= 17485 119886

3= minus58284 (5)

Hence the elimination function for conservation of diffusioncurrent with simultaneous elimination of kinetic and charg-ing current can be given as E4 [7] simultaneous eliminationof 119868119896and 119868119888 with conservation of 119868

119889

119891 (119868) = minus1165711986812+ 17485119868 minus 58284119868

2 (6)

As a result of elimination the reversible current of a substancetransported to an electrode surface by diffusion only is im-proved giving sharp peaks for reduction or oxidation signalsFor the irreversible current of a fully adsorbed substance thisfunction provides the characteristic signal of a peak-to-coun-terpeak form improving strongly the resolution and sensitiv-ity [7 14 15 18 20 21]Thus for the application of eliminationvoltammetry all that is needed is voltammetric data at threescan rates Once this data is fed into an appropriate elim-ination equation in MS Excel program it generates infor-mation that is useful for understanding the electrochemicalprocesses


20

10

00

minus10

minus20


I(120583

A)


(a)

00


200

150

100

50

minus50

a1

a2

c1c2

00

I(120583

A)


(b)


00

200

150

100

50

minus50

minus100

a1

a2

c1

c2

I(120583

A)


(c)


000

1300

2600

3900

5200

minus2600

minus1300


a1

a2

c1

c2

I(120583

A)



3 Experimental






610 (s 1H) 239 (br s 2H)13C NMR (CDCl

3) d 1569 1424 1320 1297 1290

1287(2C) 1285 1279 1273(2C) 1264 1224 1212 1205 1151559







3in



00

200

400

600



minus200

minus400

minus600

00

a1

a2

c1

c2

I(120583

A)










measurement

119891 (119868119889) = minus 11657 times 119868


2 (7)




00

200

400

600

800


minus200


a2IP

a2ICPPrepeak

00

a1


a9984001

f(Id)

(120583A

)

(a)

00

100

200

300

400


minus100



c3IPc1

c2

f(Id)

(120583A

)

ICP

(b)






00

500

1000



Prepeakminus500

minus1000

a1

a2

00

a9984001f(Id)

(120583A

)


(a)

00

400

800

1200



a1

a2

f(Id)

(120583A

)


(b)

00

500

1000


Prepeaksminus500

minus1000

a2

a1

a9984001


f(Id)

(120583A

)


(c)


oxidation process









1015840


119889) function




OH

H

(I)

NH

OH OH

(II) (III)

H

H

N

OHH

H

(IV)

N

OHH

H

(V)

N H

H

(VI)

H

(VII)

H

∙ ∙ ∙ ∙

∙

∙

NH2

NH2

minus2H+

H+

Ominus

Ominus

minus2eminus

+eminus

+eminus

minuseminus

+

N+





1015840


1015840






1015840





00

200

400a1

c1minus400

minus200


I(120583

A)


(a)

00

100

c1minus400

minus100

minus200

minus300

I(120583

A)



(b)

00

00

00

100

200 00Prepeak

minus200

minus100

minus06

minus06

minus04

minus03 03

minus02 02

x

x998400

x998400998400

minus200120583

200120583

IP

ICP


I(120583

A)


(c)

Prepeak

00

00

minus06minus03 03

minus200120583

200120583

c1

00

400

200

minus200

I(120583

A)




c9984001

(d)




5 Conclusion



HN

NO

OCu2+

03V H2

H2

HN

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

+H+

minus049V




Acknowledgments


References







































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


20

10

00

minus10

minus20


I(120583

A)


(a)

00


200

150

100

50

minus50

a1

a2

c1c2

00

I(120583

A)


(b)


00

200

150

100

50

minus50

minus100

a1

a2

c1

c2

I(120583

A)


(c)


000

1300

2600

3900

5200

minus2600

minus1300


a1

a2

c1

c2

I(120583

A)



3 Experimental






610 (s 1H) 239 (br s 2H)13C NMR (CDCl

3) d 1569 1424 1320 1297 1290

1287(2C) 1285 1279 1273(2C) 1264 1224 1212 1205 1151559







3in



00

200

400

600



minus200

minus400

minus600

00

a1

a2

c1

c2

I(120583

A)










measurement

119891 (119868119889) = minus 11657 times 119868


2 (7)




00

200

400

600

800


minus200


a2IP

a2ICPPrepeak

00

a1


a9984001

f(Id)

(120583A

)

(a)

00

100

200

300

400


minus100



c3IPc1

c2

f(Id)

(120583A

)

ICP

(b)






00

500

1000



Prepeakminus500

minus1000

a1

a2

00

a9984001f(Id)

(120583A

)


(a)

00

400

800

1200



a1

a2

f(Id)

(120583A

)


(b)

00

500

1000


Prepeaksminus500

minus1000

a2

a1

a9984001


f(Id)

(120583A

)


(c)


oxidation process









1015840


119889) function




OH

H

(I)

NH

OH OH

(II) (III)

H

H

N

OHH

H

(IV)

N

OHH

H

(V)

N H

H

(VI)

H

(VII)

H

∙ ∙ ∙ ∙

∙

∙

NH2

NH2

minus2H+

H+

Ominus

Ominus

minus2eminus

+eminus

+eminus

minuseminus

+

N+





1015840


1015840






1015840





00

200

400a1

c1minus400

minus200


I(120583

A)


(a)

00

100

c1minus400

minus100

minus200

minus300

I(120583

A)



(b)

00

00

00

100

200 00Prepeak

minus200

minus100

minus06

minus06

minus04

minus03 03

minus02 02

x

x998400

x998400998400

minus200120583

200120583

IP

ICP


I(120583

A)


(c)

Prepeak

00

00

minus06minus03 03

minus200120583

200120583

c1

00

400

200

minus200

I(120583

A)




c9984001

(d)




5 Conclusion



HN

NO

OCu2+

03V H2

H2

HN

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

+H+

minus049V




Acknowledgments


References







































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


00

200

400

600



minus200

minus400

minus600

00

a1

a2

c1

c2

I(120583

A)










measurement

119891 (119868119889) = minus 11657 times 119868


2 (7)




00

200

400

600

800


minus200


a2IP

a2ICPPrepeak

00

a1


a9984001

f(Id)

(120583A

)

(a)

00

100

200

300

400


minus100



c3IPc1

c2

f(Id)

(120583A

)

ICP

(b)






00

500

1000



Prepeakminus500

minus1000

a1

a2

00

a9984001f(Id)

(120583A

)


(a)

00

400

800

1200



a1

a2

f(Id)

(120583A

)


(b)

00

500

1000


Prepeaksminus500

minus1000

a2

a1

a9984001


f(Id)

(120583A

)


(c)


oxidation process









1015840


119889) function




OH

H

(I)

NH

OH OH

(II) (III)

H

H

N

OHH

H

(IV)

N

OHH

H

(V)

N H

H

(VI)

H

(VII)

H

∙ ∙ ∙ ∙

∙

∙

NH2

NH2

minus2H+

H+

Ominus

Ominus

minus2eminus

+eminus

+eminus

minuseminus

+

N+





1015840


1015840






1015840





00

200

400a1

c1minus400

minus200


I(120583

A)


(a)

00

100

c1minus400

minus100

minus200

minus300

I(120583

A)



(b)

00

00

00

100

200 00Prepeak

minus200

minus100

minus06

minus06

minus04

minus03 03

minus02 02

x

x998400

x998400998400

minus200120583

200120583

IP

ICP


I(120583

A)


(c)

Prepeak

00

00

minus06minus03 03

minus200120583

200120583

c1

00

400

200

minus200

I(120583

A)




c9984001

(d)




5 Conclusion



HN

NO

OCu2+

03V H2

H2

HN

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

+H+

minus049V




Acknowledgments


References







































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


00

500

1000



Prepeakminus500

minus1000

a1

a2

00

a9984001f(Id)

(120583A

)


(a)

00

400

800

1200



a1

a2

f(Id)

(120583A

)


(b)

00

500

1000


Prepeaksminus500

minus1000

a2

a1

a9984001


f(Id)

(120583A

)


(c)


oxidation process









1015840


119889) function




OH

H

(I)

NH

OH OH

(II) (III)

H

H

N

OHH

H

(IV)

N

OHH

H

(V)

N H

H

(VI)

H

(VII)

H

∙ ∙ ∙ ∙

∙

∙

NH2

NH2

minus2H+

H+

Ominus

Ominus

minus2eminus

+eminus

+eminus

minuseminus

+

N+





1015840


1015840






1015840





00

200

400a1

c1minus400

minus200


I(120583

A)


(a)

00

100

c1minus400

minus100

minus200

minus300

I(120583

A)



(b)

00

00

00

100

200 00Prepeak

minus200

minus100

minus06

minus06

minus04

minus03 03

minus02 02

x

x998400

x998400998400

minus200120583

200120583

IP

ICP


I(120583

A)


(c)

Prepeak

00

00

minus06minus03 03

minus200120583

200120583

c1

00

400

200

minus200

I(120583

A)




c9984001

(d)




5 Conclusion



HN

NO

OCu2+

03V H2

H2

HN

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

+H+

minus049V




Acknowledgments


References







































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


OH

H

(I)

NH

OH OH

(II) (III)

H

H

N

OHH

H

(IV)

N

OHH

H

(V)

N H

H

(VI)

H

(VII)

H

∙ ∙ ∙ ∙

∙

∙

NH2

NH2

minus2H+

H+

Ominus

Ominus

minus2eminus

+eminus

+eminus

minuseminus

+

N+





1015840


1015840






1015840





00

200

400a1

c1minus400

minus200


I(120583

A)


(a)

00

100

c1minus400

minus100

minus200

minus300

I(120583

A)



(b)

00

00

00

100

200 00Prepeak

minus200

minus100

minus06

minus06

minus04

minus03 03

minus02 02

x

x998400

x998400998400

minus200120583

200120583

IP

ICP


I(120583

A)


(c)

Prepeak

00

00

minus06minus03 03

minus200120583

200120583

c1

00

400

200

minus200

I(120583

A)




c9984001

(d)




5 Conclusion



HN

NO

OCu2+

03V H2

H2

HN

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

+H+

minus049V




Acknowledgments


References







































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


00

200

400a1

c1minus400

minus200


I(120583

A)


(a)

00

100

c1minus400

minus100

minus200

minus300

I(120583

A)



(b)

00

00

00

100

200 00Prepeak

minus200

minus100

minus06

minus06

minus04

minus03 03

minus02 02

x

x998400

x998400998400

minus200120583

200120583

IP

ICP


I(120583

A)


(c)

Prepeak

00

00

minus06minus03 03

minus200120583

200120583

c1

00

400

200

minus200

I(120583

A)




c9984001

(d)




5 Conclusion



HN

NO

OCu2+

03V H2

H2

HN

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

+H+

minus049V




Acknowledgments


References







































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


HN

NO

OCu2+

03V H2

H2

HN

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

H

H

N

NO

OCu2+

H2

H2

+H+

minus049V




Acknowledgments


References







































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

research article electrochemical studies of betti base and...

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