Spectra Convoluted

##The theoretical spectra, obtained through TDDFT calculations using the M06-2X functional and the def2-TZVP basis set with 50 excited electronic states, were convoluted using a Lorentzian function with a full width at half maximum (FWHM) of 12~nm. The black curve represents the pyrazine molecule, red corresponds to 2-aminopyrazine, green to 2,3-diaminopyrazine, blue to 2,5-diaminopyrazine, and pink to 2,6-diaminopyrazine. In the same figure, the inset in the upper right corner displays the bar representation of the original transitions.

Theoretical spectra bar obtained by TDDFT (M06-2X/def2-TZVP) of pyrazine.

Theoretical spectra bar obtained by TDDFT (M06-2X/def2-TZVP) of 2-Aminopyrazine.

Theoretical spectra bar obtained by TDDFT (M06-2X/def2-TZVP) of 2,3-Diaminopyrazine.

Theoretical spectra bar obtained by TDDFT (M06-2X/def2-TZVP) of 2,5-Diaminopyrazine.

Theoretical spectra bar obtained by TDDFT (M06-2X/def2-TZVP) of 2,6-Diaminopyrazine.

Transitions of pyrazine

TD-DFT calculated energy, wavelengths (λ), oscillator strengths (f) in arbitrary units, and molecular orbital contributions to the first three electronic transitions of pyrazine. Orbitals 20 and 22 are HOMO and LUMO of pyrazine molecule, respectively.
Excited_State Wavelength_nm freq Transition Coefficient
1 220.31 0.1123 18 → 23 0.22654
20 → 22 0.66966
2 182.39 0.1036 18 → 22 -0.25963
20 → 23 0.65461
3 154.46 0.3568 18 → 22 0.64333
20 → 23 0.25592

Transitions of 2-Aminopyrazine

TD-DFT calculated energy, wavelengths (λ), oscillator strengths (f) in arbitrary units, and molecular orbital contributions to the first three electronic transitions of aminopyrazine. Orbitals 25 and 26 are HOMO and LUMO of 2-aminopyrazine molecule, respectively.
Excited_State Wavelength_nm freq Transition Coefficient
1 258.33 0.108 23 → 27 -1.12960
25 → 26 0.69235
2 206.26 0.2429 23 → 26 0.11351
25 → 27 0.67659
3 166.62 0.133 21 → 26 -0.14787
23 → 26 0.64135
23 → 27 -0.12594
25 → 27 -0.10884
25 → 29 0.10206

Transitions of 2,3-Diaminopyrazine

TD-DFT calculated energy, wavelengths (λ), oscillator strengths (f) in arbitrary units, and molecular orbital contributions to the first three electronic transitions of 2,3-Diaminopyrazine. Orbitals 29 and 30 are HOMO and LUMO of 2,3-diaminopyrazine molecule, respectively.
Excited_State Wavelength_nm freq Transition Coefficient
1 260.88 0.1816 27 → 31 -0.12050
29 → 30 0.69193
2 212.04 0.1679 27 → 30 0.17499
29 → 31 0.67838
3 165.25 0.2559 25 → 30 0.23633
27 → 31 0.59383
28 → 32 -0.18747
29 → 30 0.10663
29 → 33 -0.13700

Transitions of 2,5-Diaminopyrazine

TD-DFT calculated energy, wavelengths (λ), oscillator strengths (f) in arbitrary units, and molecular orbital contributions to the first three electronic transitions of 2,5-Diaminopyrazine. Orbitals 29 and 30 are HOMO and LUMO of 2,5-diaminopyrazine molecule, respectively.
Excited_State Wavelength_nm freq Transition Coefficient
1 298.79 0.0891 29 → 30 0.69826
2 220.67 0.3226 29 → 31 0.68900
3 165.00 0.2990 26 → 30 0.68174

Transitions of 2,6-Diaminopyrazine

TD-DFT calculated energy, wavelengths (λ), oscillator strengths (f) in arbitrary units, and molecular orbital contributions to the first three electronic transitions of 2,6-Diaminopyrazine. Orbitals 29 and 30 are HOMO and LUMO of 2,6-diaminopyrazine molecule, respectively.
Excited_State Wavelength_nm freq Transition Coefficient
1 272.29 0.0543 28 → 30 0.57152
29 → 30 0.39380
2 268.88 0.1215 28 → 30 -0.39235
29 → 30 0.57038
3 214.88 0.1712 27 → 30 0.13569
29 → 31 0.68059

Cartesian coordinates (xyz) optimized at DFT/M062-X/def2-TZVP

## **pyrazine cartesian coordinates (xyz) optimized at DFT/M062-X/def2-TZVP**
C      0.049254     0.000000     0.095662
N      0.000807     0.000000     1.422402
C      1.169968    -0.000000     2.051415
C      2.375614    -0.000000     1.360541
N      2.424064    -0.000000     0.033796
C      1.254907     0.000000    -0.595219
H      3.320566    -0.000000     1.891718
H      1.274485     0.000000    -1.679012
H     -0.895696     0.000000    -0.435521
H      1.150388    -0.000000     3.135218
## **2-aminopyrazine cartesian coordinates (xyz) optimized at DFT/M062-X/def2-TZVP**
N     0.000000     0.000000     0.000000
C     0.000000     0.000000     1.400000
C     1.212436     0.000000     2.100000
N     2.476833     0.000000     1.370000
C     2.476833     0.000000    -0.030000
C     1.264397     0.000000    -0.730000
N    -1.264397     0.000000     2.130000
H     1.212436     0.000000     3.189000
H     3.419934     0.000000    -0.574500
H     1.264397     0.000000    -1.819000
H    -1.076186     0.000000     3.142658
H    -1.804506     0.840991     1.881171
## **2,3-diaminopyrazine cartesian coordinates (xyz) optimized at DFT/M062-X/def2-TZVP**
C      0.107037     0.078253     0.125555
N      0.100128     0.228941     1.460201
C      1.258127     0.213700     2.071222
C      2.472823     0.072406     1.343869
N      2.469541    -0.097101     0.045486
C      1.276127    -0.104001    -0.570752
N      1.318355     0.392688     3.445153
N      3.671923     0.060695     2.040557
H      1.279511    -0.246567    -1.643547
H      1.998590    -0.194279     3.909229
H      0.405430     0.349979     3.875614
H     -0.852765     0.093784    -0.374212
H      4.471530     0.088336     1.423777
H      3.725509     0.745147     2.783031
## **2,5-diaminopyrazine cartesian coordinates (xyz) optimized at DFT/M062-X/def2-TZVP**
C      0.031308     0.078231     0.030538
N     -0.002362     0.105549     1.358218
C      1.150730     0.088099     2.005449
C      2.375537     0.041919     1.336238
N      2.409205     0.014579     0.008554
C      1.256115     0.032030    -0.638676
N     -1.177106     0.155864    -0.649087
N      3.583952    -0.035695     2.015853
H      1.296137     0.016632    -1.722890
H     -1.969126    -0.072525    -0.067532
H     -1.201197    -0.295948    -1.549142
H      1.110702     0.103464     3.089664
H      4.375971     0.192664     1.434289
H      3.608058     0.416129     2.915903
## **2,6-diaminopyrazine cartesian coordinates (xyz) optimized at DFT/M062-X/def2-TZVP**
N      0.063181     0.127704     0.009822
C      0.109732     0.061880     1.336149
C      1.329284    -0.043985     2.019621
N      2.472985    -0.083054     1.358247
C      2.440025    -0.019207     0.038473
C      1.219669     0.088314    -0.643326
N     -1.090681     0.054519     2.002710
H      1.361770    -0.101866     3.101185
H      3.380836    -0.046453    -0.498480
N      1.168102     0.205139    -2.010448
H     -1.084760     0.324066     2.971352
H     -1.879770     0.374941     1.465276
H      0.264468     0.032808    -2.420217
H      1.956225    -0.133815    -2.534783