Electrochemical data of Co(II) complexes containing phenanthroline functionalized ligands

The data presented in this paper are related to the research article entitled “Electrochemical properties of a series of Co(II) complexes, containing substituted phenanthrolines” (Ferreira et al., 2018) [1]. This paper presents detailed electrochemical data of eight octahedral Co(II) complexes containing functionalized phenanthrolines-ligands. The data illustrate the shift in the CoIII/II and CoII/I redox couples due to different substituents on the phenanthrolines. Polypyridine Co(II) and Co(III) complexes exhibit properties as potential mediators in dye-sensitized solar cells (DSSCs) (Gajardo and Loeb, 2011; Yu et al., 2011) [2], [3]. The ability of a compound to act as a redox mediator to be used in DSSC, depends on the redox potential of the compound (Grätzel, 2005) [4]. Accurate data of the CoIII/II redox couple is presented here.


a b s t r a c t
The data presented in this paper are related to the research article entitled "Electrochemical properties of a series of Co(II) complexes, containing substituted phenanthrolines" (Ferreira et al., 2018) [1]. This paper presents detailed electrochemical data of eight octahedral Co(II) complexes containing functionalized phenanthrolines-ligands. The data illustrate the shift in the Co III/II and Co II/I redox couples due to different substituents on the phenanthrolines. Polypyridine Co(II) and Co(III) complexes exhibit properties as potential mediators in dye-sensitized solar cells (DSSCs) Yu et al., 2011) [2,3]. The ability of a compound to act as a redox mediator to be used in DSSC, depends on the redox potential of the compound (Grätzel, 2005) [4]. Accurate data of the Co III/II redox couple is presented here.
& 2018 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Subject area
Chemistry More specific subject area Electrochemistry Type of data Table, text file, graph, figure How data was acquired BAS 100B/W electrochemical analyzer (Electrochemical studies).

Data format
Raw and Analyzed.
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Data
The data presented in this paper are related to the research article entitled "Electrochemical properties of a series of Co(II) complexes, containing substituted phenanthrolines" [1]. This paper presents detailed electrochemical data of eight octahedral Co(II) complexes containing functionalized phenanthrolines-ligands. Polypyridine Co(II) and Co(III) complexes exhibit properties as potential mediators in dye-sensitized solar cells (DSSCs) [2,3]. The ability of a compound to act as a redox mediator to be used in DSSC, depends on the redox potential of the compound [4]. The data of the eight functionalized phenanthroline-Co(II) complexes, namely tris(5-nitro-1,10-phenanthroline)Cobalt (II) nitrate, [Co(5-NO 2 -phen) 3 ](NO 3 ) 2 (1), tris (4,7- (8), is presented in this contribution, see Fig. 1 for the structures of 1-8.
Cyclic voltammograms of the complexes 1-8, are presented in Figs. 2-9 and tabulated in Tables 1-8. The electrochemical data is obtained in CH 3 CN for ca 0.002 mol dm À 3 (or saturated) analyte solution. Complexes 3-8, all have three reversible peaks, namely the Co III/II redox couple (peak 1), the Co II/I redox couple (peak 2) and the ligand reduction peak (peak 3). For complex 2 the ligand reduction peak (peak 3) is irreversible and for complex 1 the irreversible peak 2 is NO 2 -ligand based. Data at scan rates 0.05-5.00 V s À 1 are provided. Data for the irreversible anionic nitrate oxidation peak at ca 1.63 V vs FcH/FcH þ , is not included in the tables. The data obtained in this study, compare good with available published data on some of the complexes, namely complex 2 [5], complex 4 [6-9], complex 7 [9] and complex 8 [9], obtained under different experimental conditions (different solvents, scan rates and supporting electrolytes). Cyclic voltammograms of complex 1 at scan rates of 0.05 V s À 1 (lowest peak current) À 5.00 V s À 1 (highest peak current). All scans initiated in the positive direction. Fig. 3. Cyclic voltammograms of complex 2 at scan rates of 0.05 V s À 1 (lowest peak current) À 5.00 V s À 1 (highest peak current). All scans initiated in the positive direction.  Cyclic voltammograms of complex 4 at scan rates of 0.05 V s À 1 (lowest peak current) À 5.00 V s À 1 (highest peak current). All scans initiated in the positive direction. Fig. 6. Cyclic voltammograms of complex 5 at scan rates of 0.05 V s À 1 (lowest peak current) À 5.00 V s À 1 (highest peak current). All scans initiated in the positive direction. Fig. 4. Cyclic voltammograms of complex 3 at scan rates of 0.05 V s À 1 (lowest peak current) À 5.00 V s À 1 (highest peak current). All scans initiated in the positive direction. Fig. 8. Cyclic voltammograms of complex 7 at scan rates of 0.05 V s À 1 (lowest peak current) À 5.00 V s À 1 (highest peak current). All scans initiated in the positive direction. Fig. 9. Cyclic voltammograms of complex 8 at scan rates of 0.05 V s À 1 (lowest peak current) À 5.00 V s À 1 (highest peak current). All scans initiated in the positive direction. Cyclic voltammograms of complex 6 at scan rates of 0.05 V s À 1 (lowest peak current) À 5.00 V s À 1 (highest peak current). All scans initiated in the positive direction.

Experimental design, materials, and methods
Electrochemical studies by means of cyclic voltammetry (CV) were performed either on 0.002 mol dm À 3 or on saturated compound solutions of the complexes in dry acetonitrile, containing 0.1 mol dm À 3 tetra-n-butylammoniumhexafluorophosphate ([ n (Bu 4 )N][PF 6 ]) as supporting electrolyte, under a blanket of purified argon, at 25°C, utilizing a BAS 100B/W electrochemical analyzer. A threeelectrode cell was used, with a glassy carbon (surface area 7.07 Â 10 À 6 m 2 ) working electrode, Pt auxiliary electrode and a Ag/Ag þ (0.010 mol dm À 3 AgNO 3 in CH 3 CN) reference electrode [10], Table 2 Electrochemical data (potential in V vs FcH/FcH þ ) in CH 3 CN for ca 0.002 mol dm À 3 of complex 2 at indicated scan rates in V s À 1 . Peak 1 is the Co III/II redox couple, peak 2 the Co II/I redox couple.  Table 4 Electrochemical data (potential in V vs FcH/FcH þ and current in A) in CH 3 CN for ca 0.002 mol dm À 3 of complex 4 at indicated scan rates in V s À 1 . Peak 1 is the Co III/II redox couple, peak 2 the Co II/I redox couple and peak 3 the ligand reduction peak.   Table 5 Electrochemical data (potential in V vs FcH/FcH þ and current in A) in CH 3 CN for ca 0.002 mol dm À 3 of complex 5 at indicated scan rates in V s À 1 . Peak 1 is the Co III/II redox couple, peak 2 the Co II/I redox couple and peak 3 the ligand reduction peak.  Table 6 Electrochemical data (potential in V vs FcH/FcH þ and current in A) in CH 3 CN for ca 0.002 mol dm À 3 of complex 6 at indicated scan rates in V s À 1 . Peak 1 is the Co III/II redox couple, peak 2 the Co II/I redox couple and peak 3 the ligand reduction peak.  Table 7 Electrochemical data (potential in V vs FcH/FcH þ and current in A) in CH 3 CN for ca 0.002 mol dm À 3 of complex 7 at indicated scan rates in V s À 1 . Peak 1 is the Co III/II redox couple, peak 2 the Co II/I redox couple and peak 3 the ligand reduction peak. mounted on a Luggin capillary [11]. Scan rates for the CVs were 0.050─5.000 V s À 1 . Successive experiments under the same experimental conditions showed that all oxidation and reduction potentials were reproducible within 0.010 V under our experimental conditions. Electrochemical data in Tables 1-8 is obtained from the cyclic voltammograms presented in Figs. 2-9. Potentials tabulated are referenced against the FcH/FcH þ couple, as suggested by IUPAC [12].