Structure of cobalt (II) perchlorate adsorbed on silica gel surface chemically modified with benzimidazole molecule

Abstract

Mo lé cu las de ben zi mi da zol co va len te men te li ga das à su per fí cie da si li ca gel, ≡SiL (onde L = N-propilbenzimidazol), ad sor vem Co(ClO 4 ) 2 de sol ven te não aquo so for man do com ple xos na su per fí cie se gun do a re a ção: m ≡SiL + Co(ClO 4)2 → ( ≡SiL) mCo(ClO 4)2. As cons tan tes de equi lí brio e ca pa ci da de de ad sor ção, fo ram de ter mi na das apli can do-se a equa ção de L ang mu ir for ne cen do res pec ti va men te, b = 3.0 x 10 3 L mol -1 e Ns = 0.098 x 10 -3 mol g -1. O me tal está li gado atra vés do áto mo de ni tro gê nio e o íon per clo ra to não está co or de na do. O es tu do de ESR mos trou que o com ple xo pos sui es sen ci al men te uma ge o me tria com dis tor ção te tra go na l, com os elé trons dos qua tro ni tro gê ni os in te ra gin do com o ion me tá li co cen tral co bal to n o pla no equa to ri al. So men te uma es pé cie com ple xa foi de tec ta da na su per fí cie.Co va lently at ta ched ben zi mi da zo le mo le cu les on si li ca gel sur fa ce, ≡SiL (whe re L = N-propylbenzimidazole), ad sorbs Co(ClO 4)2 from non-aqueous sol vent by for ming a sur fa ce com plex ac cor ding to the re ac ti on: m ≡SiL + Co(ClO 4)2 → ( ≡SiL) mCo(ClO 4)2. The equi li brium cons tant and the ad sorp ti on ca pa city, de ter mi ned by ap plying the Lang mu ir equa ti on were b = 3.0 x 10 3 L mol -1 and Ns= 0.098 x 10 -3 mol g -1 , res pec ti vely. The me tal is bon ded through the ni tro gen atom and the per chlo ra te ion is not co or di na ted. The ESR study in di ca ted t hat the com plex has es sen ti ally an oc ta he dral ge o metry with te tra go nal dis tor ti on, with the elec trons of the four ni tro gen atoms in te rac ting with the co balt cen tral me tal ion in the equa to ri al pla ne. Only one com plex spe ci es was de tec ted on the sur fa ce. Key words: si li ca gel, ben zi mi da zo le, co balt-benzimidazole sur fa ce com plex, co balt electron spin re so nan ce, si li ca gel mo di fi ed with ben zi mi da zo le Intro duc ti onOrga nic mo le cu les con ta i ning ni tro gen atoms have been che mi cally bon ded to a si li ca gel sur fa ce in or der to ad sorb me tal ions from aque ous or non aque ous sol vents [1][2][3][4][5] . As in so lu ti on pha se, many com plex spe ci es may be for med at the so lid-solution in ter fa ce by the re ac ti on of the me tal ion with the im mo bi li zed func ti o nal or ga nic mo le cu le [6][7][8] . Tech ni ques such as 13 C CPMAS NMR 9,10 and elec tron spin re so nan ce (ESR) 8,11 have been used to de ter mi ne the structu res of the se com plex spe ci es. The se cond tech ni que has been par ti cu larly use ful for cop per com ple xes 10,12 .Co balt (II) is ad sor bed from ace to ne so lu ti on by the atta ched ben zi mi da zo le yi el ding a pale blue com plex 13 . The ad sorp ti on of the me tal ion oc curs ac cor ding to the re ac tion: m ≡SiL + CoX 2 → ( ≡SiL) m CoX 2 , whe re ≡SiL is the atta ched ne u tral func ti o nal or ga nic group on the si li ca sur fa ce. The step wi se com plex for ma ti on, which con sists of a ch...

Determination of Copper in Different Ethanolic Matrices Using a Chloropropyl Silica Gel Modified with a Nanostructured Cubic Octa(3‐aminopropyl)octasilsesquioxane

“…The experimental results are expressed by the sorption isotherms obeying the relation / . The maximum number of moles of adsorbed metal ions ( má x ), called the specific sorption capacity [34], is equal to the number of moles of metal ions adsorbed when the concentration ( ) of the metal tends to the saturation limit (1),…”