Synthesis, characterization and optical studies New acid dyes and their metal complexes based on substituted phenols forleather: Technology Journal of Applied Researchand

Availableonlineatwww.sciencedirect.com

Journal of Applied Research and Technology

www.jart.ccadet.unam.mx JournalofAppliedResearchandTechnology15(2017)346–355

Original

New acid dyes and their metal complexes based on substituted phenols for leather: Synthesis, characterization and optical studies

Ghulam Hussain

, Nasir Abass

, Ghulam Shabir

, Makshoof Athar

, Aamer Saeed

, Rashid Saleem

, Farman Ali

, Misbahul Ain Khan

aInstituteofChemistry,UniversityofthePunjab,Lahore,Pakistan

bDepartmentofChemistry,Quaid-I-AzamUniversity,Islamabad45320,Pakistan

cR&DManagerShafiResoChemLahorePakistan

dDepartmentofChemistry,HazaraUniversity,Mansehra21300,Pakistan

eDepartmentofChemistry,theIslamiaUniversityofBahawalpur,Bahawalpur,Pakistan Received12October2016;accepted2March2017

Availableonline6August2017

Abstract

Thepresentinvestigationdealswithsynthesisofnewaciddyesfrom4-amino-1-(4-sulfophenyl)-3-methyl-5-pyrazoloneandphenolderivatives andtheirmetalcomplexes(Cu(II)andFe(II)).Thephenolderivativesinclude4-chlorophenol,4-nitrophenol,4-hydroxybenzenesulfonicacid, 2-nitrophenol-4-sulfonicacid,resorcinolandbisphenolAandbisphenolS.Thenewlysynthesizeddyeswereappliedtocrustleathertoassesstheir dyeingproperties.Thefastnesspropertiesofunmetallizeddyeswerelessascomparedtometalcomplexesduetothestronginteractionofmetals withleatherprotein.ThestructuresofthesedyeswerealsoconfirmedbyUV,FTIRandNMRstudies.

©2017UniversidadNacionalAutónomadeMéxico,CentrodeCienciasAplicadasyDesarrolloTecnológico.Thisisanopenaccessarticleunder theCCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).

Keywords: 4-Amino-1-(4-sulfophenyl)-3-methyl-5-pyrazolone;Phenolderivatives;Metalcomplexes;Applications

1. Introduction

Azocompoundsarenon-naturallyoccurringnitrogencom- pounds continuouslyreceiving attention inscientific research (Kirkan&Gup,2008;Otutu,2013;Sefero˘glu,2009).Azodyes constitute the largestgroupof Azo compoundsand the most widely used colorants in the industry. Several derivatives of pyrazole(azo)werethesubjectofresearchbecauseofavari- ety of applications. The applications of the azodyes include their useincoloringfibers,duetotheir affinityfor wooland silk(Patel&Patel,2011),photoelectronics(Sekar,1999),opti- calstorage technology(Wang, Shen,&Xu,2000),biological reactions (Weglarz-Tomczak& Gorecki, 2012),printing sys- tems(Abe,Mano,Yamaya,&Tomotake,1999;Dharmalingam, Ramasamy,&Balasuramanian,2011)aswellas inanalytical

∗Correspondingauthor.

E-mailaddresses:[email protected],[email protected] (A.Saeed).

PeerReviewundertheresponsibilityofUniversidadNacionalAutónomade México.

(Abdalla,El-Haty,Adam,&Hassan,2013;Amin,Mohammed,

&Mousa,2003)andfoodchemistry(Almeida,Stephani,Dos Santos,&Oliveira,2009).Besidethesemanyazocompounds havebeensynthesizedwithanindustrialandmedicalaim.The coordinationcomplexesoftransitionmetalswithazo-ligandsare alsofocusofthecurrentattractionduetotheinterestingphys- ical,chemical,photophysicalandphotochemical,catalyticand different materialproperties.Metalcomplex dyesplayavery important roleinthetextile industry.Chromium,Cr(III)and cobaltCo(III)complexesareusedmostfrequentlyforthedye- ingofwoolandsyntheticpolyamides(Kocaokutgen,Erdem,&

Gümrükc¸güoglu,1998).

Photophysicalandcoloristicpropertiesofthedyesaremod- ifiedinthecaseofaggregateformation(molecularassociation) insolution. Theself-association of dyesin solutionisdueto theinteractionsbyVanderWaalsforces,hydrogenbondsand hydrophobic interactions (Radulescu-Grad, Muntean, Todea, Verdes,&Andelescu,2015).Thedyeaggregationisaffectedby parameterssuchasdyeconcentration,dyestructure,pH,tem- perature,solventsandionicstrengths(Goftar,Moradi,&Kor, 2014).

http://dx.doi.org/10.1016/j.jart.2017.03.002

1665-6423/©2017UniversidadNacionalAutónomadeMéxico,CentrodeCienciasAplicadasyDesarrolloTecnológico.Thisisanopenaccessarticleunderthe CCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).

Inthepresentwork,twonewseriesofazo-dyes,havingFe andCu²⁺asmetalizingionweresynthesized,characterizedand appliedtoleather.Atthesametime,spectrophotometricanalysis wasalsoperformedforthequalitativestudyofligandaciddyes andtheirmetalcomplex.

2. Experimental

2.1. Materialsandmethods

All commercial products were purchased from Sigma- Aldrich. Solvents were purified and dried by the standard methods.Meltingpointsweredeterminedinopencapillarytubes onaStuartmeltingpointapparatus.TheFTIRspectrawererun inthesinglebeamNicoletIR100(Fourier-Transform);while UVofallthesamplesweretakeninwaterusing UV-Genesys spectrophotometer.Theirmassspectraldatawereobtainedfrom watersGCTpremierspectrometer.The¹HNMRand¹³CNMR spectrawererecorded inDMSO-d6 using NMRBrukerDPX 400spectrophotometeroperatingat300and75MHzfor¹Hand

13CNMRrespectively.TMSwasusedasinternalstandardwith the deuteriumsignalof the solvent as the lockandchemical shiftsδrecordedinppm.Theelementalanalysis(C,H,N,S)of thecompoundswasperformedusingFlashEA1112elemental analyzerwhilethepHwasmonitoredusingPortablepHMeter ModelPHB4.CompoundswereroutinelycheckedbyTLCon silicagelGplatesusingthreedifferentelutingsolventsdepend- ingonthepolaritydisparity.Thesolventsystemsarepetroleum ether:chloroform (9:1, v/v), petroleumether:chloroform (6:4, v/v)andchloroform:methanol(9:1,v/v). Also,thedeveloped plates were visualized using a UV lamp for the presence of spotsandRfvaluesweredulycalculated.Allofthecrudeprod- uctswereisolatedassolidsandpurified.Fastnesstolightwas assessedinaccordancewithBS1006-1978. Rubbingfastness was checked with an Atlas Crock meter in accordance with AATCC TM 8-1961 and the wash fastness was determined accordingtoISO:765-1979(Maradiya&Patel,2002;Sakoma, Bello,&Yakubu,2012).

2.2. Generalprocedureforthesynthesisof

1-(p-sulphophenyl)-3-methyl-5-pyrazolonebasedaciddyes

Synthesisof aciddyesandtheir metalcomplexes involves three-stepprocedurewhichisasfollows.

2.2.1. Nitrosationof

p-sulphophenyl-3-methyl-5-pyrazolone(SPMP)

1-(p-sulfophenyl)-3-methyl-5-pyrazolone (1) (25.4g, 0.1mol) was suspended in H2O (250ml). Hydrochloricacid (45ml)wasaddedtothiswellstirredsuspension.Thereaction mixture was cooled to 0–5^◦C in an ice bath. A solution of NaNO2 (6.9g, 0.1mol) inH2O (25ml)previously cooled to 0^◦C,wasthenaddedoveraperiodof35minwithstirring.The stirringwascontinuedforanhourmaintainingthesametemper- ature,withapositivetestfornitrousacid.Laterontheexcessof nitrousacidwasdestroyedwithrequiredamountofsulphamic

oximewasreducedbystirringin200mlwatercontaining85ml HCland23gzincmetalatboilfor4h.Oncompletionofreac- tion,pHofthereactionmixturewasraisedto9with6NNaOH, and precipitated the 1-(p-methylphenyl)-3-methyl-4-amino pyrazolones.

2.2.2. Diazotizationandcouplingwithphenolderivatives Tothewellstirredicejacketedaqueoussolution(2.69g)of1- (p-sulphophenyl)-3-methyl-4-aminopyrazolone(at0–5^◦C)was addedconc.HCl(3.5ml)andsodiumnitritesolution(0.7gin 2mlH2O).Thereactionmixturewasvigorouslystirredfor1h at the above mentioned temperature toobtain the diazonium saltof 1-(p-sulphophenyl)-3-methyl-4-aminopyrazolone. The diazoniumcompoundformedinthiswaywascoupledtovari- ouscouplermentionedpreviouslytosynthesizeourdyes.Thus 1.285g(0.010mol)4-chlorophenol(5a)wasdissolvedin200ml watercontaining0.45gNaOHandcoupledwithprepareddiazo.

Thecouplingwasfacilitatedusingsodiumcarbonateasanacid bindingagent.Thereactionmixturewasgiven4–5htocomplete thecouplingat30–35^◦C.Thedyewascooledtoroomtempera- ture.ItspHwasreducedto4.5byHClandfiltered.Thecakewas driedinovenat70–75^◦Ctillconstantweight.Byadoptingthe sameprocedureotherdyes6b–fwerepreparedfromcouplers 5b–fasshowninScheme1.

2.2.3. Metallizationofaciddyes

For the synthesis of metal complexes (iron complex), pH of 25ml(0.005mol) ofdye6awasreduced to6.5withHCl.

Then it was heated to 70^◦C andto it 5ml (0.005mol Fe²⁺) solutionofferroussulfate(FeSO4·7H2O)wasaddeddropwise.

Mixingandheatingatthistemperaturewascontinuedforfurther 1.0hourtillthemetallizationwascompleted,asshownbythe comparative TLC. Thedye wascooled toroomtemperature;

itspHwasreduced to1.0withconc.HCl.Thenitwassalted outwithsodiumchloride,filteredanddriedinovenat80^◦Ctill constantweight.

Similarly,copper(II)complexesofdye6awerepreparedby treatingdyewithCuSO4·5H2Oat65–70^◦Cwithmetaltoligand mole ratio1:1. Inthisway complexes 7a–lweresynthesized fromrespectivedyeligands(seesupplementaryinformation).

2.2.3.1. 6a(C16H13ClN4O5S). Orange,(76%).λmax(nm):460.

FTIR (KBr,cm⁻¹) νmax: 3255(OHstr.),3050(C C Hstr.), 2927(CH2str.),1653(C Ostr.),1595,1541(C Caromatic, C N),1498 (N Nstr.),1422, 1340(SO3Hstr.,CH2 bend.), 1236,1155(C C,C Ostr.),1000(S Ostr.),833(Ar H),790 (C Cl str.). ¹H NMR (300MHz, DMSO-d6) δ:8.07 (1H, d, J=2.35Hz),7.95(2H,d,J=8.6Hz),7.83–7.90(1H,m),7.68 (2H,d,J=8.6Hz),6.65(1H,d,J=9.1Hz),2.20(3H,s).¹³C NMR (75MHz DMSO-d6) δ (ppm): 158.54,156.64, 147.93, 147.37,143.21,139.93,125.43,124.41,119.45,118.06,116.22 12.45.Anal.Calcd.forC16H13ClN4O5S:C,47.01;H,3.21;N, 13.71;S,7.84.Found:C,47.05;H,3.30;N,13.59;S,7.79.

2.2.3.2. 6b (C16H13N5O7S). DarkBrown,(83%).λmax (nm):

480.FTIR(KBr,cm⁻¹)νmax:3388(OHstr.),2924(CH2str.),

Scheme1.Synthesisofligandaciddyes6a–fandtheirFe(II)andCu(II)complexes(7a–l).

1666(C Cstr.),1593(C Caromatic,C C),1498,1476(N N, NO2str.),1267,1172(C Ostr.),1034(C OCstr.),821(Ar- H).¹HNMR(300MHz,DMSO-d6)δ:8.15(1H,d,J=2.4Hz), 7.942 (2H, d, J=8.7Hz), 7.81–7.92 (1H, m), 7.65 (2H, d, J=8.7Hz), 6.38 (1H, d, J=9.3Hz), 2.27 (3H, s).¹³C NMR (75MHzDMSO-d6)δ (ppm):158.0,155.28, 148.32,147.57, 144.58,138.72,128.18126.86,126.24,118.19,117.06,116.17, 12.14.Anal.Calcd.forC16H13N5O7S: C,45.83;H,3.12;N, 16.70,S,7.64.Found:C,45.78;H,3.20;N,16.58,S,7.57.

2.2.3.3. 6c(C16H14N4O8S2). Orange,(84%).λmax(nm):460.

FTIR (KBr,cm⁻¹)νmax: 3389(OHstr),3086 (C C Hstr.), 1638(N Hbend.),1619,1597(C Caromatic),1541(N Nstr.),

1500(N Hbend.),1340(SO3H,CH2str.),1185(C Ostr.),818 (Ar H).¹HNMR(300MHz,DMSO-d6)δ:11.87(1H,s,O H), 8.10(1H,d,J=2.6Hz),7.93(2H,d,J=8.6Hz),7.79–7.90(1H, m), 7.67 (2H, d, J=8.6Hz), 6.90 (1H, s, SO3H), 6.58 (1H, d, J=9.5Hz), 2.27(3H,s).¹³C NMR(75MHzDMSO-d6) δ (ppm):159.12,156.48,147.72,147.17,145.23,141.33,138.62, 125.68,124.42,117.19,116.96,116.4311.81.Anal.Calcd.for C16H14N4O8S2:C,42.29;H,3.11;N,12.33,S:14.11.Found:

C,42.24;H,3.20;N,12.21,S:14.04.

2.2.3.4. 6d(C16H13N5O10S2). Orange,(81%).λmax(nm):520.

FTIR (KBr,cm⁻¹)νmax: 3449(OHstr.),3050(C C Hstr.), 1653 (C Cstr.NHbend),1619,1541(C Caromatic),1498

840(Ar H).¹HNMR(300MHz,DMSO-d6)δ:11.33(1H,s, O H),8.15(1H,d,J=2.4Hz),7.99(1H,d,J=2.4Hz),7.922 (2H,d,J=8.7Hz),7.63(2H,d,J=8.7Hz),2.23(3H,s).¹³C NMR (75MHz DMSO-d6)δ (ppm):157.05, 156.28,149.25, 147.63,144.28,142.76,140.92,127.16,125.54,119.19,116.56, 115.2012.14.Anal.Calcd.forC16H13N5O10S2:C,38.48;H, 2.62;N,14.02;S,12.84.Found:C,38.37;H,2.69;N,13.96;S, 12.88.

2.2.3.5. 6e(C32H26N8O12S3). Orange,(80%).λmax(nm):420.

FTIR(KBr, cm⁻¹) νmax: 3395(OH, NHstr.),3050 (C C H str.),2926(CH2str.),1619,1586(C Caromatic,C N),1498 (N Nstr.),1125(C Ostr.),1008(S O),872(Ar H).¹HNMR (300MHz, DMSO-d6) δ: 11.67 (1H, s, O H), 7.91 (2H, d, J=8.7Hz), 7.81–7.92(1H,m), 7.69 (2H,d, J=8.7Hz), 6.90 (1H,d,J=9.4Hz),6.78(1H,s),6.62(1H,s,SO3H),6.59(1H, d,J=9.4Hz),2.51(3H,s),1.469(6H,s).¹³CNMR(75MHz, DMSO-d6)δ (ppm):157.56, 154.89,148.97,154.64,144.47, 143.44,142.29,141.31,138.88,137.90,129.96,128.05,127.74, 126.78,119.85,118.63,117.64,115.79,115.64,115.13,115.02, 41.19,30.83,11.59.Anal.Calcd.forC32H26N8O12S3:C,47.40;

H,3.23;N,13.82;S,11.86.Found:C,47.46;H,3.31;N,13.56;

S,11.80.

2.2.3.6. 6f(C35H32N8O10S2). Brown,(83%).λmax(nm):450.

FTIR(KBr,cm⁻¹)νmax:3464(OH,NHstr.),2963(CH2str.), 1653,1593(C Caromatic),1490(N Nstr.),1338(SO3Hstr.), 1213, 1153, 1120 (C C str.), 1002 (S O), 872 (Ar H). ¹H NMR(300MHz,DMSO-d6)δ:11.30(1H,s,O H),7.94(2H, d,J=8.7Hz),7.82–7.93(1H,m),7.67(2H,d,J=8.7Hz),6.98 (1H,d,J=9.4Hz),6.81(1H,s),6.58(1H,d,J=9.4Hz),6.42 (1H,s,SO3H),2.47(3H,s).¹³CNMR(75MHz,DMSO-d6)δ (ppm):158.77,155.9,147.61,145.61,143.86,143.25,141.63, 139.81,136.75,130.25,127.91,125.78,119.80,118.31,116.73, 115.94,115.23, 11.59. Anal.Calcd. for C35H32N8O10S2: C, 53.29;H,4.09;N,14.21;S,8.13.Found:C,53.35;H,4.13;N, 14.04;S,8.20.

2.3. Dyeingmethod

Dyesolution (10ml,0.4%, w/v) was takenin adye-bath.

ThepH of thedye-bath wasadjustedto6.5byaddingacetic acidsolution(1.0ml,10%,w/v)solution.Thetotalvolumeof thedye-bathwasadjustedto100mlbyaddingrequiredamount ofwater.Theleatherswatcheswereintroducedintothedye-bath withstirring.Thecontentofthedye-bathwasstirredfor1hat 25–30^◦C.Thetemperaturewasthengraduallyraisedto55^◦C overperiodofhalfhourandmaintainedforonehour.Thedye- bathwaskeptrotatingduringtheprocessofdyeing.Then2.0ml formicacidwasaddedtoadjustpHto2.0fordyefixation.After this,thespentdyeliquorwastakenin250mlvolumetricflask.

Theswatcheswerewashedwithcoldwaterandthecombined solutionofdyeliquorandwashingswasthenfurtherdilutedto 250mlwithwater.Theabsorbanceofthissolutionwasmeasured tofindouttheexhaustionofdyeonleather.Thedyedswatches weredriedandmountedonshadecard.Aweighedamountof

dissolvestheunfixeddyefromswatchandfromtheabsorbance ofthissolutionpercentagefixationwaschecked.

3. Resultsanddiscussion

3.1. Synthesisandspectralcharacterizationofligandacid dyesandtheirmetalcomplexes

Synthesisofaciddyesandtheiriron(Fe,II)andcopper(Cu, II)complexeswerepreparedinfivestepprocedureasshownin Scheme1.SPMP [1-(4-sulphophenyl)3-methyl-2-pyrazolin-5- one]wasnitrosatedat0–5^◦CusingNaNO2andHClasdescribed byKnorr.Thenitrosocompoundwasfilteredtoremovesome terrymaterial.Theclarifiednitrosoderivative[thatusuallyexists inanoximeform(asindicatedbyitsFTIR)]wassaltedoutby commonsalt. Itwasdriedafterfiltration.Reductionofoxime wascarriedat100–105^◦CusingzincandHCl.Theoximeand zincwerealternativelyaddedinsmallportionsinboilingHCl solution.Thereductionwascompletedasthesolutionbecame colorless. A small amount of additional zinc dust was also addedtopreventaerialoxidationoncooling.Theresultantamine hydrochloridewasquenchedto−7^◦C.Theexcessiveun-reacted zincwasremovedbyfiltration.Thisaminehydrochloridewas diazotizedusinganaqueoussolutionofNaNO2(6.9gdissolved in250mlofsolution)andHClat−5to−2^◦Ctoavoidthefor- mationofRubazoicacid,whichisautomaticallyformedduring thisreactionwithincreasingtemperatureduetooxidizingaction ofnitrousacid,formedinsitu.Thediazoniumsaltpreparedin thiswaywascoupled withdifferent parasubstitutedphenols, like,p-chlorophenol,p-nitrophenol,phenol-4-suphonicacid,2- nitrophenol-4-suphonic acidandbisphenols (bisphenolS and bisphenolA).Thecouplingwascarriedoutinalkalinemedium at pH 8–9. The synthesis of this diazo has been confirmed fromX-raystructureofitscrystal.Couplinginalkalinemedium occurredatorthopositiontothehydroxylgroupsofphenoland bisphenolderivatives,asparapositionwasblocked.Thesynthe- sizeddyes6a–fwereprecipitatedoncompletionofreactionby reducingthepHofsolutionto1.0withHCl.Thefiltereddyes weredriedandpurifiedinethanol.Metallizationofthesedyes wasdonebytreatingtheiralkalinesolutionwithFeSO4·7H2O andCuSO4·5H2Oat65–70^◦C.Ittookabout4–5htocomplete themetallizationas wasobservedbytakingtheTLCof reac- tionmixturein9:1chloroformandmethanol.Dyes(7a–l)were precipitated withaddition of HCl, filtered and driedin oven at80^◦C.Thesedyeswereagain purifiedfromethanol,dried, weighedanddeterminedthepercentageyield.Theseunmetal- lized dyes 6a–f are tridentate ligands which formcomplexes with iron(Fe, II) andcopper(Cu, II) through 1:1 metal and ligand stoichiometricratio (Fig.2).Incaseof Fe²⁺ andCu²⁺

complexes lonepairsof electronsaredonated bytwo oxygen atomsand onenitrogenatom of thediazo linkage, while the otherthreecoordinationnumbersofthesemetalshavebeensat- isfiedbythreewatermolecules.Thecomplexformationpattern hasbeenverifiedbytheUV–visspectrophotometricstudiesof thesedyes7a–l.IncaseofIRspectraofcompoundsdifferent moieties showed stretching and bending bands characteristic

OH

3500 40

50 60 70 80 90

3000 2500

Wavenumber (cm–1)

Transmittance

2000 1500 1000

2OH2

H2O HO₃S

N N

CH3

O N N Fe⁺²O

NO2

Fig.1.FTIRspectrumofIroncomplexofdye6b.

of the synthesized compounds. The infrared spectra of the synthesized acid dyes and their metal complexes exhibited absorptionpeaksduetoO H,Ar H,C H,C O,C C,N N, SO3H,C OandO Mstretchingandbendingvibrationsat3399, 3050,2926,1550,1472, 1272,1164,1004,834,610cm⁻¹ as depictedfromtheirFTIRspectra(Fig.1).Similarlyothermetal complexeshavebeenconfirmedfromtheirrespectiveIRspectra.

1HNMRand¹³CNMRspectraweretakenforliganddyes whichshowed characteristicsignalsfor different protonsand carbonsatdifferentpositionswhichevidencedthesynthesisof dyes.Incaseofcompounds6bsignalforhydroxylgroupwas absent duetoexchangeableproton withDMSO.The doublet signalofmutuallycoupledsetoffourprotonsofphenylgroup substitutedwith sulfonicgroup atpresent 7.95 and7.68ppm havingcouplingconstantrespectivelysignals8.6Hz.Themul- tipletsignalforoneprotonofaromaticringofcouplingmoiety

ispresentat7.83–7.90ppmwhilethesameringbearinganother singleprotonshowssignalat8.07ppmwithcouplingconstant 2.35Hzwhichevidencedthemetarelationshipwithanotherpro- tonatthesamering.Themethylgrouppresentatpyrazolonering exhibitedsingletsignalat2.20ppm(Fig.2).In¹³CNMRspec- trumthesignalformethylgroupispresentat12.14ppm.There aretensignalsintherange117.06–158.00ppmfordifferentcar- bon nucleiinthe compound(Fig.3).Inthiswayotherligand aciddyes wereconfirmedfromtheirrespective¹HNMRand

13CNMRspectra.Whenthe¹HNMRspectra ofmetalcom- plexdyeswereconductedtheyshowedverybroadanddistorted signalsduetoparamagneticnatureofmetalsusedforcomplex- ationandthesotheNMRstudyofcomplexeswasnotfruitful forstructureelucidationbutinotherwordsthedistortedbroad signalsprovedthecomplexationwhenthe¹HNMRofligands aciddyesandcomplexeswerecompared.

HO₃S

N N

CH

8.158 8.150 7.957 7.928 7.821 7.812 7.790 7.781 7.672 7.644 6.402 6.371 3.971 2.518 2.296

3

OH N N

HO

14 13 12 11 10 9

1.00 1.91 1.22 2.00 0.92 4.33

8 7 6 5 4 3 2 1 0 ppm

NO₂

Fig.2.¹HNMRspectrumofligandaciddye6b.

158.00 155.28 148.32 147.57 144.38 138.72 126.86 126.24 118.19 117.06 40.73 40.45 40.17 39.89 39.61 39.34 39.06 12.14

HO₃S

CH₃ NO₂

OH

200 180 160 140 120 100 80 60 40 20 0 ppm

HO N N N

N

Fig.3.¹³CNMRspectrumofligandaciddye6b.

3.2. Dyeingpropertiesofsubstitutedligandaciddyesand theirmetalcomplexes(6a–fand7a–l)

Thedyeingpropertiesofp-substitutedphenolsandbisphenol dyeshavebeenfoundtobeveryattractive.Almostallproperties havebeenfoundtobeofveryhighvalue(4–5).Liganddyeshad lowvaluesas perourexpectationduetothe presenceof free hydroxylgroups.Thedyeingpropertiesofthesedyesaregiven inTable1.

Almostallun-metalizedp-substitutedphenoldyeshavebeen foundtobedifferent;bothin2%and5%dyedleathers,along withavariationofthedepthofshades.Thiscanbeattributed tothedifferenceofchromophoricsystemsinalldyes.However, itisclearfromshadesthatthisdifferenceisduetothediffer- ence of p-substituentsin differentphenols. All of the phenol homologueshaddarkandreddershadesexceptp-sulphophenol substituteddyes.The variationof the depth canbeattributed totheparticipationofperipheralgroup’svariationindifferent phenols.

Almostalliron-metalizedphenoldyeshadbeenfoundtobe similar(olive);bothin2%and5%dyedleathers,alongwitha variationof depthofshades.However,it isclearfromshades thatthedepthdifferenceisduetothedifferenceofp-substituents indifferentphenols.Allthephenolhomologueshaddarkand reddershadesexcept p-sulphophenol.Bothnitro phenols had similarshadeswithyellowishtone.Almostallcopper-metalized phenolhadbeenfoundtobedifferent;bothin2%and5%dyed leathers, along witha variationof depth of shades.This can beattributedtothe differenceofchromophoricsystems inall dyes. However,it isclear from shades that thisdifference is duetothedifferenceofp-substituentsindifferentphenols.All

of thephenolhomologueshaddarkandreddershadesexcept p-sulphophenol. Both nitro phenols had similar shades with yellowishredtone.

Thedyeingpropertiesofbis-phenolsdyeshavebeenfound to be very good and attractive. Almost all properties have been found to be of very high value (4–5). The dyes with bisphenol-A have been found to be much darker as com- paredtothedyesofbisphenol-S.Thiscanbeattributedtothe n→п* electronictransitions occurring insulphone groupof bisphenol-S.

Asitisclearfromdyeshadesamongtheun-metalizedbisphe- noldyes,thedyewithbisphenol-Ahadahighcolorvaluewhile bisphenol-Sdyegavealowcoloryieldonleather.Thisdifference canbeascribedtotheparticipationofsulphonegrouppresent inbisphenol-S.

Itisclearfromthedepthofshadesthatironmetalizedbisphe- noldyeshadgreatercolorvaluethantheirparentun-metalized bisphenol dyes. These dyes are much greener as they were expected. The iron complex with ligand acid dye based on bisphenol-Shadalowcolorvaluewhilebisphenol-Adyepro- videdadarkershadeandhighcoloryieldonleatheralongwith amuch reddereffect. Thisdifferencecanbeattributed tothe participationofsulphonegroupinbisphenol-S.

Similarly,coppermetalizedbisphenoldyeshadalsogreater color value than their parent un-metalized bisphenol dyes.

Thesedyesare muchredderasper ourexpectation.Thecop- per complex dye with bisphenol-A had a high color value while bisphenol-S dye gavea lighterand low coloryield on leatheralongwithamuchreddereffect.Thisdifferencecanbe attributedtotheparticipationofsulphonegroupinbisphenol-S (Figs.4and5).

Table1

Fastnesspropertiesofligandaciddyes(6a–f)andtheirmetalcomplexes(7a–l).

Dye 2%shadeonleather 5%shadeonLeather Penetration Washingfastness Lightfastness Perspirationfastness

6a YellowishOrange ReddishOrange 2 2–3 2–3 3–4

7a Olive DarkOlive 5 4–5 5 5

7b YellowishOrange ReddishBrown 3 3–4 3–4 4–5

6b Orange YellowishOrange 2 2–3 2–3 3–4

7c Olive DarkOlive 5 4–5 5 5

7d YellowishOrange YellowishBrown 3 3–4 3–4 4–5

6c YellowishOrange YellowishOrange 3 3–4 2–3 3–4

7e LightOlive DarkOlive 5 4–5 5 5

7f YellowishOrange YellowishOrange 4 3–4 3–4 4–5

6d Tan YellowishBrown 3 3–4 3–4 3–4

7g OliveBrown DarkOlive 5 4–5 5 5

7h YellowishOrange ReddishOrange 3 3–4 3–4 4–5

6e GreenishBeige ReddishBeige 2 2–3 2–3 3–4

7i Beige ReddishBeige 4 3–4 4–5 4–5

7j GreenishBeige ReddishBeige 5 4–5 5 5

6f GoldenYellow YellowishOrange 3 3–4 3–4 4–5

7k Olive YellowishBrown 4 3–4 4–5 4–5

7l YellowishOrange Reddishorange 5 4–5 5 5

6a

7a

7b 7d 7f 7h 7j 7I

7c 7e 7g 7i 7k

6b 6c 6d 6e 6f

Fig.4.2%shadeofdyes6a–fand7a–lonleather.

6a

7a

7b 7d 7f 7h 7j 7I

7c 7e 7g 7i 7k

6b 6c 6d 6e 6f

Fig.5.5%shadeofdyes6a–fand7a–lonleather.

UV–visdataofligandaciddyes(6a–f)andtheirFe(II)andCu(II)complexes(7a–l).

Dye Molecularformula Molecularmass Powder/solutioncolor λmax(nm)

6a C16H13ClN4O5S 408.82 Orange/ReddishOrange 460

7a C16H17ClFeN4O8S 516.69 Olive/OliveBrown 490

7b C16H13ClCuN4O6S 488.36 Tan/ReddishViolet 500

6b C16H13N5O7S 419.37 DarkBrown/ReddishOrange 480

7c C16H17FeN5O10S 527.24 Gray/YellowishBrown 440

7d C16H13CuN5O8S 498.91 Tan/ReddishYellow 460

6c C16H14N4O8S2 454.43 Orange/YellowishOrange 460

7e C16H18FeN4O11S2 562.31 OliveBrown/YellowishBrown 430

7f C16H14CuN4O9S2 533.98 Brown/YellowishOrange 460

6d C16H13N5O10S2 499.43 Orange/ReddishOrange 520

7g C16H17FeN5O13S2 607.31 Gray/YellowishOrange 470

7h C16H13CuN5O11S2 578.98 Tan/ReddishBrown 500

6e C32H26N8O12S3 810.79 Orange/ReddishOrange 420

7i C32H34Fe2N8O18S3 1026.54 Brown/ReddishBrown 360

7j C32H29Cu2N8O14S3 1008.93 Tan/Yellow 370

6f C35H32N8O10S2 788.81 Brown/YellowishOrange 450

7k C35H40Fe2N8O16S2 1004.56 Gray/Reddishbrown 440

7l C35H32Cu2N8O12S2 735.44 DarkBrown/YellowishOrange 450

3.3. Opticalstudiesofdyes

Incaseofopticalstudies,dyeswereconductedtheirUV–vis studies to observe the changes rendered by metal complex formation.TheUV–visdatapresentedinTable2issupported by combined UV–vis spectra of ligand acid dyes 6a–f. The un-metalized dye-6a was an orange dye with λmax 460nm while on metallization of this with iron, Olive Brown dye (Dye-7a) was produced with λmax 490nm undergoing a bathochromic shift of 30nm along with hypochromic effect.

Metallizationofdye6awithcopperresultedintheformationof aReddishVioletdye(Dye-7b)withλmax500nmandshowed a bathochromic shift of 40nm with hypochromic shift in intensity.

Threedyeswerepreparedwithp-nitrophenol.Thefirstone being an un-metalized dyeand the other two were iron and coppercomplexes, respectively. The detailedproperties of p- nitrophenoldyes are given inTable 1. The unmetallized dye 6bwasanorangedyewithλmax480nmwhichdevelopedyel- lowish brown dye on complexation with iron (Dye 7c) with λmax 440nm. It showed hypsochromic shift of 40nm along withhyperchromiceffect. Similar behavior was observedfor coppercomplexes ofthisdye.Thedye6cwaspreparedfrom phenol-4-sulphonicacidwhichwasYellowishOrangecolored dyehavingλmax460nm.Metallizationofthedye6cwithiron andcopperproducedyellowishbrown(Dye 7e)andReddish Orangedye(Dye7f) dyeswithλmax430 and460nmrespec- tivelywhichexhibitedpatternofhypsoandhypochromiceffects.

Dyes7g and7hwere iron andCu complexes of 1:1type of dye6d.The un-metalizeddye6dwasaReddishOrange dye withλmax520nm.ItsmetallizationwithIronproducedayel- lowish browndye (Dye7g) withλmax 470nm andenhanced the absorbance intensity thanparent dyeand showed a hyp- sochromicshiftof50nm.Whilemetallizationofthesamewith copperresultedintheformationofaReddishBrowndye(Dye 7h)withλmax500nmandahypsochromicshiftof20nmwas observed.

Inthebisphenolseriessixdyeswereprepared.Forthispur- posetwodifferentbisphenols,namely4,4^-dihydroxybiphenyl sulphone(BPS),4,4^-dihydroxybiphenylpropane(BPA),were used as couplers. Threedisazo dyes were accomplishedwith bisphenol-S.Thefirstdyebeinganun-metalizedoneandanother two were iron and copper bis-metalcomplexes, respectively.

Theun-metalizeddye6ewasaReddishOrangedyewithλmax

420nm.ItsmetallizationwithironproducedaReddishBrown dye (Dye7i) withλmax 410nm anda hypsochromicshiftof 10nmwasseen. Whilethemetallizationofsamedye6ewith copperresultedintheformationofaYellowdye(Dye7j).Ithad λmax370nmandabsorbance1.6,showedahypsochromicshift of50nm.Themetalcomplexesofdye6fwithironandcopper exhibitedthesimilarbehaviorlikebisphenolSdyemetalcom- plexesinabsorptionintensitywhilenoconceivablechangewas foundinλmaxposition.FromthedetailedUV–visstudyofdyes itwasgatheredthatmetalcomplexesofliganddyesbearingelec- tronwithdrawinggroupsshowedhypsochromicshitandthose havingelectrondonatinggroupsshowedbathochromicshiftin absorbancewhichisinaccordancewithwellestablishedUV–vis absorptionpatternofcompounds(Figs.6and7).

–1 0 1 2 3 4

Absorbance

Wavelength (nm)

200 300 400 500 600 700 800

6a 6b 6c 6d 6e 6f

Fig.6.UV–visspectrumofligandaciddyes6a–f.

1.6

2.0

1.5

1.0

0.5

0.0 1.4

1.2 1.0

0.8 0.6

0.4

0.2 0.0

2.5

2.0

1.5

1.0

0.5

0.0

–0.5

1.8

2.0

1.5

1.0

0.5

0.0 1.6

1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 –0.2

2.5

2.0

1.5

1.0

0.5

0.0

–0.5

200 300 400 500

6a

6b 7c 7a 7d

7b

6c

6d 7g 7e 7h

7f

6e 6f

7k 7I 7i

7k Wavelength (nm)

Wavelength (nm)

Wavelength (nm) Wavelength (nm)

Wavelength (nm) Wavelength (nm)

AbsorbanceAbsorbanceAbsorbance AbsorbanceAbsorbanceAbsorbance

600 700 800

200 300 400 500 600 700 800

200 300 400 500 600 700 800

200 300 400 500 600 700 800

200 300 400 500 600 700 800

200 300 400 500 600 700 800

Fig.7.Effectofmetalionsonλmaxofligandaciddyes6a–f.

4. Conclusions

Aseriesof newaciddyes 6a–fandtheir metalcomplexes (7a–l) have been synthesized in high yields from 1-(p- sulphophenyl)-3-methyl-4-aminopyrazolonewithp-substituted phenols andbisphenols.Metalcomplexationhaschangedthe absorptionmaximaofaciddyeswhichresultedinhypsochromic shiftinironandcoppercomplexesofthoseaciddyeswhichcar- riedelectronwithdrawinggroupslikenitroandsulfonicwhile

iron andcoppercomplexes of dyesbearingelectron donating groupscausedbathochromicshifts. Moreover,metal complex dyes hadbetterapplicationpropertiesonleatherascompared toliganddyes duetoelevatedsubstantivityowingtoelectron deficientmetalsandpolarsubstituents.

Conflictofinterest

Theauthorshavenoconflictsofinteresttodeclare.

Supplementarydataassociatedwiththisarticlecanbefound, intheonlineversion,atdoi:10.1016/j.jart.2017.03.002.

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