Guanine: A Combined Study Using Vibrational Spectroscopy and Theoretical Methods
Table 1
Calculated (isolated molecule and condensed phase) and measured (asymmetric unit) geometric parameters for guanine.
Dihedrals
Isolatedmolecule[a]
Condensedphase[b]
Asymmetricunit[c]
Angles
Isolatedmolecule
Condensedphase
Asymmetricunit
H10–N2–C2–N3
143.4
178.0
174.3
H10-N2-C2
116.7
123.3
118.8
H10–N2–C2–N1
−39.1
−1.8
−6.7
H11-N2-H10
113.3
120.3
120.2
H11–N2–C2–N3
10.9
3.0
10.0
H11-N2-C2
111.6
116.2
119.2
H11–N2–C2–N1
−171.6
−176.8
−170.9
N2-C2-N1
115.7
118.4
117.0
N2–C2–N1–H
−2.7
3.1
2.1
N2-C2-N3
119.9
119.5
119.6
N2–C2–N1–C6
−177.2
−179.7
179.5
N1-C2-N3
124.3
122.1
123.4
N2–C2–N3–C4
176.4
−179.5
179.7
C2-N1-H
120.1
119.3
125.2
C2–N3–C4–N9
−179.3
178.9
177.7
C6-N1-H
114.3
115.6
110.3
C2–N3–C4–C5
1.6
−0.8
−0.6
C2-N1-C6
125.5
125.1
124.6
C2–N1–C6–C5
0.1
−0.9
−0.1
N1-C6=O
121.4
120.2
120.0
N3–C4–C5–C6
−1.5
0.4
0.1
C2-N3-C4
114.3
115.5
114.0
N3–C4–N9–C8
−179.4
−179.4
−179.1
N3-C4-C5
124.2
124.8
125.3
N3–C4–C5–N7
179.4
179.5
179.0
C5-C6-N1
108.7
112.4
111.8
N3–C2–N1–C6
0.1
0.6
−0.4
N3-C4-N9
125.4
125.6
124.6
N3–C2–N1–H
174.7
−176.6
−178.8
C5-C4-N9
110.4
109.6
110.2
C4–N9–C8–H
−180.0
178.8
176.5
C4-C5-N7
105.6
106.0
106.6
C4–N9–C8–N7
0.1
−0.3
0.4
C6-C5-N7
131.4
133.8
132.4
C4–C5–C6–N1
0.6
0.5
0.2
C4-C5-C6
123.0
120.2
121.0
C4–C5–C6=O
−178.9
−179.8
179.9
C5-C6=O
129.8
127.4
128.3
C4–N3–C2–N1
176.4
0.3
0.7
C5-N7-H
125.9
129.8
131.6
C4–C5–N7–C8
−0.1
0.0
−0.3
C8-N7-H
128.0
124.0
123.2
C5–N7–C8–H
−180.0
−179.0
−176.0
C5-N7-C8
106.0
106.1
105.2
C5–N7–C8–N9
0.0
0.2
−0.1
N7-C8-N9
113.5
113.5
114.1
C5–C4–N9–C8
−0.1
0.2
−0.5
C8-N9-C4
104.5
104.9
103.9
C5–C6–N1–H
−174.8
176.4
178.5
N7-C8-H
121.7
121.6
125.0
C6–C5–N7–H
0.8
−3.9
−2.1
N9-C8-H
124.9
124.9
120.8
C6–C5–N7–C8
−179.1
179.0
178.5
C6–C5–C4–N9
179.2
−179.3
−178.4
N1–C6–C5–N7
179.4
−178.4
178.3
N9–C4–C5–N7
0.1
−0.2
0.5
N9–C8–N7–H
−179.8
−177.2
−179.6
N7–C5–C6=O
0.0
1.3
1.3
H–C8–N7–H
0.2
3.7
4.5
H–N1–C6=O
4.7
−3.3
−1.2
Bond
Isolated
Condensed
Asymmetric
H-Bonding
Condensed phase
lengths
molecule
phase
unit
N–H–X
N–H
H–X
(N)H–X
<(N–H–X)
H10–N2
101.1
104.8
84.0
N2–H10–N9
104.8
188.0
292.8
179.3
H11–N2
101.2
104.1
88.1
N2–H11–O
104.1
186.0
290.1
179.0
N2–C2
138.2
132.7
133.0
N1–H–N3
107.9
176.6
284.3
176.7
C2–N1
138.2
137.2
137.1
N7–H–O
106.1
168.5
272.0
163.6
C2–N3
130.5
132.7
133.0
N1–H
101.3
107.9
90.9
Asymmetric unit
N3–C4
136.8
133.8
135.6
N2–H10–N9
84.0
217.1
300.6
172.0
N1–C6
142.0
137.8
138.7
N2–H11–O
88.1
202.4
290.2
174.3
C4–C5
139.5
139.6
137.8
N1–H–N3
90.9
196.8
286.1
166.7
C6–C5
142.8
140.4
141.2
N7–H–O
99.6
176.7
274.2
165.4
C6=O
122.6
125.7
124.9
C4–N9
137.4
135.8
136.4
C5–N7
137.8
137.0
137.2
N7–H
100.9
106.1
99.6
N7–C8
136.4
133.9
134.3
C8–H
108.2
109.4
97.1
N9–C8
132.0
132.6
132.8
[a]At the DFT B3LYP/6-31G** level of theory. [b]With the PWSCF/LDA methodology. [c]Geometric parameters obtained from X-ray diffraction data (CIF file provided. [9]).
