Experimental data for green synthesis of Zn-abietate complex from natural resin

This data article is associated with the work “Ecofriendly synthesis of Zn-abietate complex derived from Pinus elliottii resin and its application as an antibacterial pigment against S. aureus and E. coli”. The characterization data of the Zn-abietate complex obtained from Pinus elliottii resin and their reactional intermediary (Na-abietate) are reported. The Na-abietate was prepared with purified Pinus resin and sodium hydroxide (≥ 99%) in a stoichiometric ratio of 1:1. For the Zn-abietate synthesis was used ZnSO4 and Na-abietate solutions were at mild temperature and stirring without using organic solvents to ensuring the green character of the synthesis. Spectroscopic and structural characterization was consistent with an octahedral complex involving three carboxylate ligands per metal ion. X-ray photoelectron spectroscopy (XPS) analysis of the Na-abietate salt confirms the presence of carbonyl groups, carbon-oxygen atoms simple bonds (O-C/O=C), and carboxylate groups oxygen atoms (O-C=O). Analysis of the Zn LMM Auger, for the Zn-abietate complex, indicates the presence of zinc atoms with oxidation state Zn2+, this is supported by the distance between Zn 2p3/2 and 1p1/2 in the XPS spectrum. Together, these data will be useful for the structural representation of the samples.

supported by the distance between Zn 2p 3/2 and 1p 1/2 in the XPS spectrum. Together, these data will be useful for the structural representation of the samples.  Table   Subject Inorganic Chemistry Specific subject area Science Materials Type of data Electronics, equipped with a monochrome X-ray source Al K α). The XPS spectra were collected at a take-off angle of 45 o in relation to the energy of the analyser electron and the spot size was 200 μm. Passage energy (PE) of 20 eV was used for the high energy resolution spectra (Zn 2p, Na 1s, O 1s, and C 1s). The energy resolution was 0.6 eV. For the charge compensation of build-up charge on the sample surface during measurements, a dual beam charge neutralization composed of an electron gun ( < 1eV) and an argon ion gun ( < 10 eV) was used. The XPS spectra were analysed using the CASA-XPS software.

Value of the Data
• A green, simple, low-cost method to produced zinc abietate. Data obtained show the ligand coordination, the chemical species present on the surface, and the chemical composition of the samples. • The method can be useful to avoid using organic solvents and the data can contribute to identifying components and structure. • Data can be used to determine the structure and properties of the materials and the metals.   The chemical structure of the deprotonated abietic acid corresponding to the peak at m/z 301.17 in Fig. 2 A is represented in Fig. 3 . Fig. 4 shows the chemical structure of the dimeric form of the abietic acid (peak at m/z 603.41 in Fig. 2 A). The structural representation of the Zn-abietate complex with a Zn 2 + atom bonded to 3 abietate ligands [C 20 H 29 O 2 ] 3 − is showed in Fig. 5 , this corresponds to peak at m/z 967.66 in the mass spectrum ( Fig. 2 A). The chemical structures resulting from the oxidation of the C = C bonds to the keto form are shown in Figs. 6-11 , the oxidation process can be observed in the Zn-abietate mass spectrum by a difference of m/z 16 between its consecutive main peaks ( Fig. 2 B).

Data Description
The Na-abietate and Zn-abietate XPS survey spectra are presented in Fig. 12 , the chemical elements found are labelled. Fig. 13 shows the C 1s spectrum of the Na-abietate. Fig. 14 A and 14 B show the Zn LMM Auger spectrum and Zn 2p of the Zn-abietate sample, respectively. Energydispersive X-ray spectroscopy (EDX) spectrum of Na-abietate and Zn-abietate and the percentages of the elements are presented in Fig. 15 , and Table 1 , respectively. The raw data of the EDX and XPS analysis found in DOI: 10.17632/n4fhxhz77b.1 .   Fig. 1 describes the Zn-abietate complex synthesis method with its intermediary steps, Naabietate. Pinus elliottii var. elliottii resin was used as reaction precursor, this was chosen due to its low cost, abundance, antibacterial properties, and being a regional reforestation product. The   reaction has 2 steps as shows the Fig. 1 , in the first, 164.0 g of purified Pinus resin [1] is mixed with 21.67 g of NaOH dissolved in 200 mL of deionized water; the molar proportion used in this step was 1:1. This mixture is kept under stirring at 90 °C for 3h, all reactional water is evaporated in the course of the reaction for the formation of a hygroscopic salt (Na-abietate). In the second step occurs the Zn-abietate formation from Na-abietate synthetized before; 30.1 g (0.0933 mol) of Na-abietate is dissolved in 50 mL of deionized water, for a faster dissolution the water is heated to 80 °C. This solution is reserved to cooling. A second solution is prepared with 9.0 g (0.0311 mol) of zinc sulfate (ZnSO 4 .7H 2 O, 99%, Quimex) in 30 mL of deionized water. Then, both solutions are mixed dropwise under stirring, and colds in an ice bath. The Zn-abietate formation occurs immediately by the substitution reaction according to Eq. (1 ). This complex is washed out with deionized water and vacuum filtered, dried in the oven at 70 °C for 5 h, mechanically macerated, and sieved until obtaining the necessary granulometry for application as pigment. The powder-like product shows a coloration of light yellow, and hydrophobic properties The molar proportions for Zn-abietate formation in the second step was 3:1 (Na-abietate:Zn 2 + ).

Mass spectrometry
The largest peak in the mass spectrum ( Fig. 2 ) is the ion observed in m/z + 301, corresponding to the deprotonated abietic acid theoretical molecular mass [C 20 H 29 O 2 ] ( Fig. 3 ). The structure of the abietic acid dimeric form ( Fig. 4 ) corresponding to the peak in m/z + 603 in the mass spectrum ( Fig. 2 ). The Zn-abietate complex structural representation formed by Zn 2 + bonded to 3 abietate ligands [C 20 H 29 O 2 ] 3 − ( Fig. 5 ) is responsible for the peak in m/z + 967 in the mass spectrum. The peaks in m/z + 983, m/z + 999, m/z + 1015, m/z + 1031, m/z + 1047, m/z + 1063, correspond to structures responsible in Figs. 6-11 . These structures exhibit a characteristic progression with a difference m/z of 16 units for each peak, related to atoms from the oxidation of the C = C bonds to the keto form.

Chemical analysis by X-ray photoelectron spectroscopy (XPS)
The chemical composition was evaluated by X-ray photoelectron spectroscopy (XPS). All binding energies were calibrated using the carbon C 1s peak at 284.6 eV. The elemental analysis of the Zn-abietate complex and Na-abietate salt was performed using XPS survey scans. The elements detected in samples were C, O, and Na for Na-abietate; and C, O, Na, and Zn for Znabietate. XPS survey scan revealed lower contamination with Na in the Zn-abietate sample. The sodium observed in the survey spectrum can be associated with remaining residues from the first synthesis stage.
Na-abietate precursor X-ray photoelectron analysis revealed the presence of carbon (51.6 at%), oxygen (30.8 at%), sodium (16.6 at%), and sulfur (1.0 at%). The spectrum of O 1s for the Naabietate can be reproduced using five components (Gaussians-Lorentzian) centered at 531.2 eV, 533.8 eV, 535.3 eV, 536.8 eV, and 532.6 eV corresponding to the Na-O, to the carbonyl group, and/or carbon-oxygen atoms simple bonds (O-C/O = C), carboxylate group oxygen atoms (O-C = O) [2] , Na KL 1 L 23 Auger emission, and sulfate (SO 4 ) 2 − [3] , respectively. The C 1s spectrum of Naabietate ( Fig. 13 ) shows components centred at binding energies of 284.5 eV, 285.9 eV, 287.7 eV, 289.9 eV, 289.9 eV, assigned, respectively, to sp 3 carbon bonds to hydrogen atoms or other     [2] . The XPS analysis can be used to determine the coordinating metal atom oxidation state. This is important information to understand metals ion antibacterial properties as in the case of zinc [4 , 5] . For the Zn-abietate sample, the Zn LMM Auger peak centred at 987 eV  indicates that the Zn atoms have the Zn (II) oxidation state ( Fig. 14 A). In the XPS spectrum the distance between Zn 2p 3/2, and 1p 1/2 is 23 eV ( Fig. 14 B) confirming the Zn 2 + oxidation state.

Chemical analysis by EDS
The energy-dispersive X-ray spectroscopy (EDS) analysis was performed in quadruplicate. Fig. 15 shows the curves for the elements, and the percentages are summarized in Table 1 . In the Zn-abietate sample was detectable contamination sodium due to the Na-abietate formed in the first stage of synthesis. For the Na-abietate no contaminants were identified by this technique due to the low sensitivity to surface contamination of this method.