Data from X-ray crystallographic analysis and DFT calculations on isomeric azo disperse dyes

X-ray crystallography and DFT calculations were used to characterize the molecular nature and excited state properties of isomeric photostable azo dyes for textile fibers undergoing extensive sunlight exposure. Structural data in CIF files arising from X-ray analysis are reported and the complete files are deposited with the Cambridge Crystallographic Data Centre as CCDC 1548989 (https://www.ccdc.cam.ac.uk/structures/Search?Ccdcid=1548989) and CCDC 1548990 (https://www.ccdc.cam.ac.uk/structures/Search?Ccdcid=1548990). Data from calculating the vertical electronic excitation of 20 excited states for each dye and from calculating excited state oxidation potential (ESOP) and Frontier HOMO/LUMO isosurfaces are also presented. This data is related to the article “Molecular and excited state properties of isomeric scarlet disperse dyes” (Lim et al., 2018) [1].


Subject area
Chemistry, Photophysics More specific subject area Inkjet printing, Azo Dyes, Excited State Properties, X-ray Crystallography. Type of data Table, Image (x-ray, TD-DFT calculations), Figure  How data

Value of the data
The data illustrate the reliability of current day molecular modeling methods for generating equilibrium geometries of monoazo dyes that are comparable to X-ray crystal structures.
The data show essential calculations for predicting the molecular and excited state properties of organic dyes.
The data are useful for further studies on the development of synthetic dyes having high photostability.
The data show key vertical electronic excitations of 20 excited states for each dye along with the oscillator strength and molecular orbitals involved.

Data
The data arise from X-ray crystallographic analysis and computational methods in the characterization of isomeric monoazo dyes Sc2 and Sc3 for textile fibers. The data are Supplementary material for the study describing the "Molecular and excited state properties of isomeric scarlet disperse dyes" [1].
The overlay of data from X-ray and computational analysis of dyes Sc2 and Sc3 is shown in Fig. 1, to demonstrate the ability of DFT-based calculations to accurately predict the structures of these monoazo dyes. Root-mean squared (RMS) values were 0.0053 for Sc2 and 0.0001 for Sc3. Other key crystallographic data for the two dyes are summarized in Tables 1 and 2, including the associated crystal systems, space groups, molecular volumes, number of molecules per unit cell, 2θmax values, and bond lengths. The latter values are especially helpful in establishing the tautomeric form (azo vs.  hydrazone) of the dyes analyzed (cf. N1-N2, N2-C8, N4-C12 data) ( Table 3). Data for intermolecular H-bonding interactions between layers of molecules positioned parallel to each other are given in Fig. 2. The unit cell for Sc2 shows intermolecular H-bond distances between the NH 2 and CN groups (2.418 Å). Also seen are short contacts corresponding to intermolecular hydrogen bonds for Sc3, namely the NO 2 and NH 2 groups (2.188 Å), and the NH 2 and CN groups (2.512 Å).
Calculation of vertical electronic excitation energies for 20 excited states along with the oscillator strength (f) and molecular orbitals involved for each dye led to the raw data shown in Tables 4 and 5 for Sc2 and Sc3. From these data the excited state oxidation potential (ESOP) for each dye can be extracted.

Experimental design, materials, and methods
Single crystal X-ray diffraction analysis was conducted using a Bruker-Nonius X8 Apex2 diffractometer. The frame integration was performed with the program SAINT. The resulting raw data was scaled and absorption corrected using a multi-scan averaging of symmetry equivalent data using SIRPOW [2]. Structures were solved using the program SHELXT [3]. Slow evaporation of CH 2 Cl 2 solutions of Sc2 and Sc3 at room temperature gave thin plate-like single crystals that were suitable for X-ray crystallographic analysis. The equilibrium molecular geometries (EMGs) of Sc1, Sc2 and Sc3 were calculated in the neutral forms using density functional theory (DFT) employing the generalized gradient approximation (GGA) at the hybrid exchangecorrelation energy functional 3-Parameter (Exchange), Lee et al. (B3LYP) [4,5] and the full-electron basis set Density Gauss double-zeta with polarization functions (DGDZVP) [6,7], implemented in Gaussian 09. The X-ray structures of Sc2 and Sc3 were superimposed on the corresponding calculated molecular geometries and the RMS was calculated in each case. The isosurfaces of the HOMO and LUMO were extracted for each dye from the corresponding checkpoint files. In addition, TD-DFT calculations were performed on the EMGs and the geometry of the excited state structure was calculated using single point energy calculations for each dye. Vertical electronic excitation energies for 20 excited states were calculated for each dye and the excited state oxidation potential (ESOP) for each dye was extracted.