A new high-pressure benzocaine polymorph — towards understanding the molecular aggregation in crystals of an important active pharmaceutical ingredient (API)

Benzocaine (BZC), an efficient and highly permeable anaesthetic and an active pharmaceutical ingredient of many commercially available drugs, was studied under high pressure up to 0.78 GPa. As a result, new BZC polymorph (IV) was discovered. The crystallization of polymorph (IV) can be initiated by heating crystals of polymorph (I) at a pressure of at least 0.45 GPa or by their compression to 0.60 GPa. However, no phase transition from polymorph (I) to (IV) was observed. Although polymorph (IV) exhibits the same main aggregation motif as in previously reported BZC polymorphs (I)–(III), i.e. a hydrogen-bonded ribbon, its molecular packing and hydrogen-bonding pattern differ considerably. The N—H...N hydrogen bonds joining parallel BZC ribbons in crystals at ambient pressure are eliminated in polymorph (IV), and BZC ribbons become positioned at an angle of about 80°. Unfortunately, crystals of polymorph (IV) were not preserved on pressure release, and depending on the decompression protocol they transformed into polymorph (II) or (I).

Computing details

For all structures, data collection: CrysAlis PRO 1.171.38.41 (Rigaku OD, 2015); cell refinement: CrysAlis PRO 1.171.38.41 (Rigaku OD, 2015); data reduction: CrysAlis PRO 1.171.38.41 (Rigaku OD, 2015). Program(s) used to solve structure: SHELXS (Sheldrick, 2008) for BZC_a1, BZC_a3, BZC_b3; ShelXT (Sheldrick, 2015) for BZC_a2, BZC_a4, BZC_a5, BZC_b1, BZC_b2. For all structures, program(s) used to refine structure: SHELXL (Sheldrick, 2015); molecular graphics: Olex2 (Dolomanov et al., 2009); software used to prepare material for publication: Olex2 (Dolomanov et al., 2009).

4-aminobenzoic acid ethyl ester (BZC_a1)

Crystal data

C9H11NO2	F(000) = 352
Mr = 165.19	Dx = 1.224 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.1928 (6) Å	Cell parameters from 592 reflections
b = 5.4539 (5) Å	θ = 4.5–21.5°
c = 20.07 (5) Å	µ = 0.09 mm^−1
β = 91.47 (4)°	T = 295 K
V = 896 (2) Å^3	Needle, colourless
Z = 4	0.43 × 0.1 × 0.1 mm

Data collection

Xcalibur, Eos diffractometer	238 reflections with I > 2σ(I)
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	Rint = 0.099
Graphite monochromator	θmax = 27.0°, θmin = 3.9°
Detector resolution: 16.2413 pixels mm^-1	h = −10→10
ω and φ scans	k = −6→6
442 measured reflections	l = −4→4
442 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.061	H-atom parameters constrained
wR(F^2) = 0.168	w = 1/[σ^2(Fo^2) + (0.1127P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.96	(Δ/σ)max < 0.001
442 reflections	Δρmax = 0.09 e Å^−3
100 parameters	Δρmin = −0.07 e Å^−3
123 restraints

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refined as a 2-component twin.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.2304 (6)	0.4101 (11)	0.1336 (12)	0.090 (19)
N1	0.9728 (8)	0.1430 (11)	0.2044 (11)	0.07 (3)
H1A	1.0542	0.1890	0.1786	0.086*
H1B	0.9737	−0.0196	0.2046	0.086*
C4	0.5209 (5)	0.4076 (11)	0.1421 (8)	0.091 (19)
C3	0.6626 (7)	0.5269 (10)	0.1235 (8)	0.096 (19)
H3	0.6559	0.6666	0.0970	0.115*
C2	0.8142 (5)	0.4375 (12)	0.1446 (8)	0.098 (19)
H2	0.9090	0.5174	0.1322	0.118*
C1	0.8241 (6)	0.2288 (11)	0.1842 (8)	0.095 (19)
C6	0.6824 (9)	0.1094 (10)	0.2028 (8)	0.096 (19)
H6	0.6891	−0.0303	0.2293	0.115*
C5	0.5308 (6)	0.1988 (12)	0.1817 (8)	0.102 (19)
H5	0.4361	0.1189	0.1942	0.122*
C7	0.3627 (11)	0.4953 (15)	0.1216 (12)	0.076 (18)
O2	0.3664 (7)	0.6853 (10)	0.0791 (13)	0.086 (18)
C8	0.2142 (9)	0.7863 (16)	0.055 (2)	0.074 (18)
H8A	0.1562	0.8611	0.0910	0.089*
H8B	0.1462	0.6578	0.0354	0.089*
C9	0.2526 (9)	0.9823 (17)	0.0009 (19)	0.076 (18)
H9A	0.2862	0.9020	−0.0391	0.114*
H9B	0.3386	1.0875	0.0172	0.114*
H9C	0.1565	1.0781	−0.0086	0.114*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.057 (4)	0.100 (4)	0.11 (6)	0.000 (3)	−0.008 (11)	0.023 (10)
N1	0.076 (5)	0.076 (4)	0.06 (10)	0.004 (3)	0.029 (14)	0.022 (10)
C4	0.050 (5)	0.056 (5)	0.17 (6)	0.002 (4)	0.035 (13)	−0.008 (11)
C3	0.063 (5)	0.065 (5)	0.16 (6)	−0.005 (4)	−0.003 (13)	0.013 (15)
C2	0.068 (6)	0.062 (5)	0.17 (6)	−0.007 (4)	0.026 (14)	−0.006 (14)
C1	0.064 (5)	0.054 (5)	0.17 (6)	−0.003 (4)	0.027 (12)	−0.035 (13)
C6	0.078 (6)	0.057 (5)	0.15 (6)	−0.012 (5)	0.041 (17)	−0.015 (13)
C5	0.096 (7)	0.051 (5)	0.16 (6)	−0.004 (5)	0.062 (16)	−0.024 (15)
C7	0.060 (5)	0.058 (4)	0.11 (5)	0.001 (4)	0.008 (12)	0.006 (12)
O2	0.069 (4)	0.081 (4)	0.11 (5)	0.013 (3)	0.020 (9)	0.021 (11)
C8	0.058 (5)	0.091 (6)	0.07 (6)	0.009 (5)	−0.014 (12)	0.000 (16)
C9	0.080 (6)	0.084 (5)	0.06 (6)	0.006 (4)	−0.046 (15)	−0.005 (16)

Geometric parameters (Å, º)

O1—C7	1.210 (10)	C6—H6	0.9300
N1—H1A	0.8914	C6—C5	1.3900
N1—H1B	0.8871	C5—H5	0.9300
N1—C1	1.357 (8)	C7—O2	1.34 (2)
C4—C3	1.3900	O2—C8	1.44 (2)
C4—C5	1.3900	C8—H8A	0.9700
C4—C7	1.432 (12)	C8—H8B	0.9700
C3—H3	0.9300	C8—C9	1.56 (3)
C3—C2	1.3900	C9—H9A	0.9600
C2—H2	0.9300	C9—H9B	0.9600
C2—C1	1.3900	C9—H9C	0.9600
C1—C6	1.3900
H1A—N1—H1B	106.0	C6—C5—C4	120.0
C1—N1—H1A	114.1	C6—C5—H5	120.0
C1—N1—H1B	110.7	O1—C7—C4	128.5 (12)
C3—C4—C5	120.0	O1—C7—O2	117.3 (11)
C3—C4—C7	121.5 (7)	O2—C7—C4	113.9 (9)
C5—C4—C7	118.5 (7)	C7—O2—C8	118.6 (13)
C4—C3—H3	120.0	O2—C8—H8A	110.1
C4—C3—C2	120.0	O2—C8—H8B	110.1
C2—C3—H3	120.0	O2—C8—C9	108.1 (13)
C3—C2—H2	120.0	H8A—C8—H8B	108.4
C1—C2—C3	120.0	C9—C8—H8A	110.1
C1—C2—H2	120.0	C9—C8—H8B	110.1
N1—C1—C2	119.5 (5)	C8—C9—H9A	109.5
N1—C1—C6	120.5 (5)	C8—C9—H9B	109.5
C6—C1—C2	120.0	C8—C9—H9C	109.5
C1—C6—H6	120.0	H9A—C9—H9B	109.5
C1—C6—C5	120.0	H9A—C9—H9C	109.5
C5—C6—H6	120.0	H9B—C9—H9C	109.5
C4—C5—H5	120.0

4-aminobenzoic acid ethyl ester (BZC_a2)

Crystal data

C9H11NO2	F(000) = 352
Mr = 165.19	Dx = 1.264 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.24 (3) Å	Cell parameters from 690 reflections
b = 5.4015 (9) Å	θ = 4.1–20.6°
c = 19.519 (3) Å	µ = 0.09 mm^−1
β = 91.55 (6)°	T = 298 K
V = 868 (3) Å^3	Plate, colourless
Z = 4	0.44 × 0.44 × 0.1 mm

Data collection

Xcalibur, Eos diffractometer	292 independent reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	197 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.038
Detector resolution: 16.2413 pixels mm^-1	θmax = 26.8°, θmin = 3.9°
ω and φ scans	h = −1→1
Absorption correction: multi-scan CrysAlisPro 1.171.38.41 (Rigaku Oxford Diffraction, 2015) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −6→6
Tmin = 0.650, Tmax = 1.000	l = −23→24
2925 measured reflections

Refinement

Refinement on F^2	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.044	H-atom parameters constrained
wR(F^2) = 0.131	w = 1/[σ^2(Fo^2) + (0.0682P)^2 + 0.2839P] where P = (Fo^2 + 2Fc^2)/3
S = 1.16	(Δ/σ)max < 0.001
292 reflections	Δρmax = 0.05 e Å^−3
99 parameters	Δρmin = −0.09 e Å^−3
132 restraints

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.226 (3)	0.4063 (13)	0.1335 (4)	0.064 (7)
C1	0.825 (2)	0.2176 (12)	0.1825 (3)	0.055 (4)
C6	0.684 (2)	0.0959 (7)	0.2010 (2)	0.050 (4)
H6	0.6908	−0.0471	0.2274	0.061*
C5	0.533 (2)	0.1879 (11)	0.1798 (3)	0.051 (4)
H5	0.4391	0.1064	0.1922	0.062*
C4	0.524 (2)	0.4016 (12)	0.1403 (3)	0.053 (3)
C3	0.665 (2)	0.5233 (7)	0.12184 (19)	0.056 (4)
H3	0.6579	0.6663	0.0954	0.068*
C2	0.815 (2)	0.4314 (11)	0.1430 (3)	0.057 (4)
H2	0.9096	0.5128	0.1306	0.069*
N1	0.979 (4)	0.1356 (12)	0.2039 (4)	0.060 (7)
H1A	1.0555	0.1379	0.1724	0.072*
H1B	0.9731	−0.0207	0.2170	0.072*
O2	0.364 (2)	0.6840 (9)	0.0745 (2)	0.074 (8)
C8	0.210 (4)	0.7862 (16)	0.0502 (4)	0.098 (19)
H8A	0.1498	0.8514	0.0884	0.117*
H8B	0.1445	0.6586	0.0279	0.117*
C9	0.246 (2)	0.9909 (11)	0.0001 (3)	0.09 (3)
H9A	0.3098	0.9258	−0.0363	0.131*
H9B	0.3059	1.1200	0.0233	0.131*
H9C	0.1463	1.0567	−0.0186	0.131*
C7	0.358 (2)	0.4900 (19)	0.1180 (6)	0.056 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.02 (2)	0.092 (5)	0.074 (4)	0.004 (11)	−0.003 (12)	0.012 (3)
C1	0.057 (9)	0.058 (4)	0.050 (4)	−0.002 (7)	0.005 (8)	−0.004 (3)
C6	0.054 (9)	0.044 (3)	0.053 (3)	−0.016 (7)	0.007 (7)	0.009 (2)
C5	0.055 (9)	0.049 (3)	0.050 (3)	−0.019 (7)	0.002 (7)	0.001 (2)
C4	0.059 (9)	0.051 (4)	0.047 (4)	−0.007 (8)	0.000 (8)	−0.003 (3)
C3	0.059 (9)	0.052 (4)	0.059 (4)	−0.013 (7)	0.007 (7)	0.010 (3)
C2	0.057 (9)	0.053 (4)	0.062 (4)	−0.011 (8)	0.012 (8)	0.007 (3)
N1	0.03 (2)	0.072 (4)	0.074 (4)	−0.032 (11)	0.010 (11)	0.007 (3)
O2	0.07 (2)	0.073 (3)	0.079 (3)	0.012 (7)	0.015 (7)	0.018 (2)
C8	0.13 (6)	0.083 (5)	0.082 (5)	0.039 (13)	0.020 (12)	0.006 (4)
C9	0.11 (9)	0.075 (4)	0.077 (4)	0.04 (5)	0.03 (5)	0.011 (3)
C7	0.053 (12)	0.061 (5)	0.054 (5)	−0.019 (8)	0.020 (9)	−0.004 (4)

Geometric parameters (Å, º)

O1—C7	1.22 (2)	C2—H2	0.9300
C1—C6	1.3900	N1—H1A	0.8940
C1—C2	1.3900	N1—H1B	0.8837
C1—N1	1.39 (2)	O2—C8	1.45 (3)
C6—H6	0.9300	O2—C7	1.351 (11)
C6—C5	1.3900	C8—H8A	0.9700
C5—H5	0.9300	C8—H8B	0.9700
C5—C4	1.3900	C8—C9	1.513 (13)
C4—C3	1.3900	C9—H9A	0.9600
C4—C7	1.501 (8)	C9—H9B	0.9600
C3—H3	0.9300	C9—H9C	0.9600
C3—C2	1.3900
C6—C1—C2	120.0	C1—N1—H1B	109.6
C6—C1—N1	122.0 (8)	H1A—N1—H1B	104.9
C2—C1—N1	118.0 (8)	C7—O2—C8	116.8 (18)
C1—C6—H6	120.0	O2—C8—H8A	110.2
C1—C6—C5	120.0	O2—C8—H8B	110.2
C5—C6—H6	120.0	O2—C8—C9	107.5 (19)
C6—C5—H5	120.0	H8A—C8—H8B	108.5
C4—C5—C6	120.0	C9—C8—H8A	110.2
C4—C5—H5	120.0	C9—C8—H8B	110.2
C5—C4—C3	120.0	C8—C9—H9A	109.5
C5—C4—C7	117.6 (6)	C8—C9—H9B	109.5
C3—C4—C7	122.3 (6)	C8—C9—H9C	109.5
C4—C3—H3	120.0	H9A—C9—H9B	109.5
C2—C3—C4	120.0	H9A—C9—H9C	109.5
C2—C3—H3	120.0	H9B—C9—H9C	109.5
C1—C2—H2	120.0	O1—C7—C4	128.2 (10)
C3—C2—C1	120.0	O1—C7—O2	119.5 (15)
C3—C2—H2	120.0	O2—C7—C4	112.2 (13)
C1—N1—H1A	116.2

4-aminobenzoic acid ethyl ester (BZC_a3)

Crystal data

C9H11NO2	F(000) = 352
Mr = 165.19	Dx = 1.354 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 6.305 (1) Å	Cell parameters from 982 reflections
b = 5.1839 (4) Å	θ = 4.0–26.2°
c = 24.94 (8) Å	µ = 0.10 mm^−1
β = 96.25 (8)°	T = 298 K
V = 810 (3) Å^3	Plate, colourless
Z = 4	0.42 × 0.34 × 0.1 mm

Data collection

Xcalibur, Eos diffractometer	270 independent reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	225 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.052
Detector resolution: 16.2413 pixels mm^-1	θmax = 26.5°, θmin = 4.0°
ω and φ scans	h = −7→7
Absorption correction: multi-scan CrysAlisPro 1.171.38.41 (Rigaku Oxford Diffraction, 2015) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −6→6
Tmin = 0.111, Tmax = 1.000	l = −6→6
2490 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.063	H-atom parameters constrained
wR(F^2) = 0.172	w = 1/[σ^2(Fo^2) + (0.1321P)^2 + 0.4918P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max < 0.001
270 reflections	Δρmax = 0.11 e Å^−3
99 parameters	Δρmin = −0.10 e Å^−3
125 restraints

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.0175 (9)	1.1815 (8)	0.1293 (13)	0.042 (17)
O2	0.0058 (7)	0.8460 (8)	0.0760 (8)	0.063 (14)
N1	0.9037 (10)	0.6236 (12)	0.2110 (15)	0.062 (18)
H1A	0.8974	0.5688	0.2436	0.074*
H1B	0.9428	0.4992	0.1912	0.074*
C4	0.3036 (5)	0.8802 (7)	0.1418 (5)	0.039 (13)
C5	0.4169 (6)	1.0146 (7)	0.1838 (5)	0.043 (13)
H5	0.3596	1.1635	0.1972	0.052*
C6	0.6159 (6)	0.9267 (8)	0.2057 (5)	0.047 (13)
H6	0.6917	1.0167	0.2338	0.057*
C1	0.7017 (6)	0.7043 (7)	0.1856 (5)	0.043 (13)
C2	0.5884 (6)	0.5698 (7)	0.1436 (5)	0.045 (13)
H2	0.6457	0.4209	0.1302	0.054*
C3	0.3893 (6)	0.6577 (7)	0.1217 (5)	0.046 (13)
H3	0.3136	0.5677	0.0936	0.055*
C7	0.0975 (12)	0.9848 (12)	0.1161 (11)	0.038 (14)
C8	−0.1941 (11)	0.9401 (11)	0.0464 (12)	0.043 (19)
H8A	−0.2986	0.9759	0.0712	0.051*
H8B	−0.1682	1.0975	0.0271	0.051*
C9	−0.2713 (13)	0.7389 (12)	0.0088 (14)	0.06 (2)
H9A	−0.1765	0.7223	−0.0186	0.096*
H9B	−0.4115	0.7830	−0.0077	0.096*
H9C	−0.2773	0.5783	0.0277	0.096*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.043 (4)	0.046 (2)	0.04 (5)	0.012 (2)	−0.001 (14)	0.011 (9)
O2	0.026 (3)	0.043 (2)	0.11 (4)	0.000 (2)	−0.023 (9)	−0.016 (8)
N1	0.031 (4)	0.057 (3)	0.09 (6)	0.013 (3)	−0.006 (11)	0.014 (12)
C4	0.026 (3)	0.033 (2)	0.06 (4)	0.000 (2)	−0.001 (10)	0.008 (8)
C5	0.035 (4)	0.034 (3)	0.06 (4)	0.000 (2)	−0.009 (10)	0.009 (8)
C6	0.033 (3)	0.043 (3)	0.06 (4)	−0.004 (2)	−0.010 (10)	−0.002 (8)
C1	0.028 (3)	0.036 (3)	0.06 (4)	0.000 (3)	−0.004 (9)	0.014 (9)
C2	0.037 (4)	0.035 (3)	0.06 (4)	0.004 (2)	0.005 (10)	0.003 (9)
C3	0.033 (3)	0.037 (3)	0.07 (4)	−0.002 (2)	−0.003 (9)	−0.003 (8)
C7	0.029 (4)	0.037 (3)	0.05 (4)	−0.002 (3)	0.017 (10)	0.002 (9)
C8	0.033 (4)	0.049 (3)	0.05 (6)	0.007 (3)	0.008 (10)	0.021 (11)
C9	0.042 (5)	0.058 (4)	0.09 (7)	−0.012 (3)	0.000 (15)	−0.014 (12)

Geometric parameters (Å, º)

O1—C7	1.199 (13)	C4—C7	1.487 (16)
O2—C7	1.31 (3)	C5—C6	1.3900
O2—C8	1.47 (2)	C6—C1	1.3900
N1—C1	1.422 (19)	C1—C2	1.3900
C4—C5	1.3900	C2—C3	1.3900
C4—C3	1.3900	C8—C9	1.45 (3)
C7—O2—C8	118.8 (9)	C2—C1—N1	123.4 (11)
C5—C4—C3	120.0	C3—C2—C1	120.0
C5—C4—C7	119.7 (8)	C2—C3—C4	120.0
C3—C4—C7	120.2 (9)	O1—C7—O2	120.8 (18)
C4—C5—C6	120.0	O1—C7—C4	124 (2)
C1—C6—C5	120.0	O2—C7—C4	114.8 (8)
C6—C1—N1	116.6 (11)	C9—C8—O2	107.2 (9)
C6—C1—C2	120.0

4-aminobenzoic acid ethyl ester (BZC_a4)

Crystal data

C9H11NO2	F(000) = 352
Mr = 165.19	Dx = 1.365 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 6.3679 (8) Å	Cell parameters from 880 reflections
b = 5.1671 (6) Å	θ = 4.0–23.3°
c = 24.58 (8) Å	µ = 0.10 mm^−1
β = 96.25 (6)°	T = 298 K
V = 804 (3) Å^3	Plate, colourless
Z = 4	0.43 × 0.31 × 0.1 mm

Data collection

Xcalibur, Eos diffractometer	296 independent reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	223 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.049
Detector resolution: 16.2413 pixels mm^-1	θmax = 26.5°, θmin = 4.0°
ω and φ scans	h = −7→8
Absorption correction: multi-scan CrysAlisPro 1.171.38.41 (Rigaku Oxford Diffraction, 2015) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −6→6
Tmin = 0.054, Tmax = 1.000	l = −5→5
2457 measured reflections

Refinement

Refinement on F^2	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.044	H-atom parameters constrained
wR(F^2) = 0.104	w = 1/[σ^2(Fo^2) + (0.0471P)^2 + 0.3983P] where P = (Fo^2 + 2Fc^2)/3
S = 1.16	(Δ/σ)max < 0.001
296 reflections	Δρmax = 0.08 e Å^−3
99 parameters	Δρmin = −0.08 e Å^−3
142 restraints

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.0184 (5)	1.1890 (6)	0.1315 (8)	0.039 (9)
O2	0.0069 (5)	0.8480 (7)	0.0763 (6)	0.046 (7)
N1	0.9040 (6)	0.6313 (10)	0.2074 (9)	0.072 (14)
H1A	0.9428	0.4999	0.1890	0.087*
H1B	0.8961	0.5852	0.2411	0.087*
C4	0.3031 (4)	0.8843 (6)	0.1408 (4)	0.029 (6)
C5	0.4160 (5)	1.0196 (6)	0.1832 (4)	0.032 (6)
H5	0.3586	1.1677	0.1972	0.039*
C6	0.6146 (5)	0.9337 (6)	0.2047 (4)	0.037 (6)
H6	0.6901	1.0242	0.2332	0.044*
C1	0.7004 (4)	0.7124 (6)	0.1838 (4)	0.035 (6)
C2	0.5875 (5)	0.5770 (6)	0.1413 (4)	0.032 (6)
H2	0.6449	0.4289	0.1273	0.038*
C3	0.3888 (4)	0.6630 (6)	0.1198 (4)	0.033 (6)
H3	0.3133	0.5724	0.0914	0.039*
C7	0.0974 (8)	0.9895 (10)	0.1165 (9)	0.033 (6)
C8	−0.1931 (7)	0.9444 (9)	0.0490 (8)	0.036 (9)
H8A	−0.1723	1.1097	0.0317	0.044*
H8B	−0.2948	0.9669	0.0753	0.044*
C9	−0.2724 (8)	0.7405 (10)	0.0057 (10)	0.040 (10)
H9A	−0.1716	0.7228	−0.0204	0.060*
H9B	−0.4058	0.7947	−0.0128	0.060*
H9C	−0.2893	0.5771	0.0233	0.060*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.040 (2)	0.045 (2)	0.03 (3)	0.0096 (15)	−0.013 (7)	0.006 (6)
O2	0.0291 (19)	0.046 (2)	0.06 (2)	0.0050 (15)	−0.023 (5)	−0.012 (5)
N1	0.042 (3)	0.058 (3)	0.12 (4)	0.011 (2)	0.023 (9)	0.020 (8)
C4	0.027 (2)	0.032 (2)	0.029 (17)	−0.0028 (18)	0.007 (6)	0.003 (6)
C5	0.035 (2)	0.032 (2)	0.030 (18)	0.004 (2)	0.004 (6)	0.002 (7)
C6	0.036 (2)	0.042 (3)	0.032 (18)	−0.004 (2)	0.005 (6)	0.003 (6)
C1	0.030 (2)	0.038 (2)	0.035 (19)	0.001 (2)	−0.001 (7)	0.018 (7)
C2	0.038 (3)	0.029 (2)	0.030 (19)	0.004 (2)	0.008 (7)	0.009 (7)
C3	0.033 (2)	0.037 (2)	0.028 (18)	−0.0036 (18)	0.006 (6)	0.001 (6)
C7	0.030 (3)	0.038 (2)	0.031 (19)	−0.004 (2)	0.003 (6)	−0.001 (7)
C8	0.030 (2)	0.048 (3)	0.03 (3)	0.003 (2)	0.001 (6)	−0.002 (8)
C9	0.040 (3)	0.065 (3)	0.02 (3)	−0.004 (2)	−0.002 (8)	−0.004 (9)

Geometric parameters (Å, º)

O1—C7	1.221 (11)	C6—C1	1.3900
O2—C7	1.313 (19)	C1—C2	1.3900
O2—C8	1.460 (11)	C2—H2	0.9300
N1—H1A	0.8662	C2—C3	1.3900
N1—H1B	0.8668	C3—H3	0.9300
N1—C1	1.425 (10)	C8—H8A	0.9700
C4—C5	1.3900	C8—H8B	0.9700
C4—C3	1.3900	C8—C9	1.54 (2)
C4—C7	1.481 (10)	C9—H9A	0.9600
C5—H5	0.9300	C9—H9B	0.9600
C5—C6	1.3900	C9—H9C	0.9600
C6—H6	0.9300
C7—O2—C8	116.4 (6)	C4—C3—H3	120.0
H1A—N1—H1B	109.4	C2—C3—C4	120.0
C1—N1—H1A	108.4	C2—C3—H3	120.0
C1—N1—H1B	109.0	O1—C7—O2	122.4 (11)
C5—C4—C3	120.0	O1—C7—C4	124.3 (15)
C5—C4—C7	118.6 (6)	O2—C7—C4	113.3 (7)
C3—C4—C7	121.3 (7)	O2—C8—H8A	110.4
C4—C5—H5	120.0	O2—C8—H8B	110.4
C4—C5—C6	120.0	O2—C8—C9	106.7 (6)
C6—C5—H5	120.0	H8A—C8—H8B	108.6
C5—C6—H6	120.0	C9—C8—H8A	110.4
C1—C6—C5	120.0	C9—C8—H8B	110.4
C1—C6—H6	120.0	C8—C9—H9A	109.5
C6—C1—N1	117.9 (7)	C8—C9—H9B	109.5
C6—C1—C2	120.0	C8—C9—H9C	109.5
C2—C1—N1	122.1 (7)	H9A—C9—H9B	109.5
C1—C2—H2	120.0	H9A—C9—H9C	109.5
C1—C2—C3	120.0	H9B—C9—H9C	109.5
C3—C2—H2	120.0

4-aminobenzoic acid ethyl ester (BZC_a5)

Crystal data

C9H11NO2	F(000) = 352
Mr = 165.19	Dx = 1.375 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 6.3410 (7) Å	Cell parameters from 869 reflections
b = 5.1594 (5) Å	θ = 4.0–23.3°
c = 24.52 (6) Å	µ = 0.10 mm^−1
β = 96.05 (5)°	T = 298 K
V = 798 (2) Å^3	Plate, colourless
Z = 4	0.43 × 0.31 × 0.1 mm

Data collection

Xcalibur, Eos diffractometer	289 independent reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	224 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.054
Detector resolution: 16.2413 pixels mm^-1	θmax = 26.5°, θmin = 4.0°
ω and φ scans	h = −7→7
Absorption correction: multi-scan CrysAlisPro 1.171.38.41 (Rigaku Oxford Diffraction, 2015) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −6→6
Tmin = 0.020, Tmax = 1.000	l = −5→5
2437 measured reflections

Refinement

Refinement on F^2	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.043	H-atom parameters constrained
wR(F^2) = 0.121	w = 1/[σ^2(Fo^2) + (0.0968P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max < 0.001
289 reflections	Δρmax = 0.08 e Å^−3
111 parameters	Δρmin = −0.08 e Å^−3
132 restraints

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O2	0.0057 (5)	0.8484 (6)	0.0761 (6)	0.045 (6)
O1	0.0175 (4)	1.1903 (5)	0.1315 (7)	0.040 (9)
N1	0.9034 (6)	0.6310 (12)	0.2062 (9)	0.069 (15)
H1A	0.9271	0.4818	0.1927	0.083*
H1B	0.9065	0.6184	0.2410	0.083*
C4	0.3017 (7)	0.8884 (8)	0.1386 (7)	0.028 (6)
C2	0.5873 (8)	0.5781 (8)	0.1417 (9)	0.035 (6)
H2	0.6446	0.4304	0.1273	0.042*
C7	0.0977 (9)	0.9906 (9)	0.1167 (9)	0.034 (7)
C5	0.4163 (8)	1.0194 (9)	0.1824 (8)	0.032 (6)
H5	0.3575	1.1649	0.1973	0.038*
C6	0.6138 (7)	0.9359 (8)	0.2035 (8)	0.037 (6)
H6	0.6893	1.0310	0.2312	0.045*
C3	0.3893 (6)	0.6633 (7)	0.1211 (8)	0.033 (6)
H3	0.3115	0.5648	0.0943	0.040*
C8	−0.1935 (7)	0.9434 (8)	0.0494 (8)	0.033 (6)
H8A	−0.1729	1.1078	0.0315	0.040*
H8B	−0.2946	0.9680	0.0760	0.040*
C1	0.7026 (7)	0.7141 (8)	0.1844 (9)	0.036 (6)
C9	−0.2740 (8)	0.7394 (9)	0.0072 (10)	0.042 (9)
H9A	−0.1717	0.7154	−0.0186	0.063*
H9B	−0.4060	0.7959	−0.0119	0.063*
H9C	−0.2952	0.5784	0.0255	0.063*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O2	0.0301 (19)	0.0454 (18)	0.053 (18)	0.0061 (14)	−0.019 (5)	−0.012 (5)
O1	0.0393 (19)	0.0428 (18)	0.03 (3)	0.0101 (13)	−0.012 (7)	0.013 (5)
N1	0.041 (2)	0.056 (2)	0.11 (5)	0.008 (2)	0.012 (8)	0.015 (8)
C4	0.026 (2)	0.034 (2)	0.026 (18)	−0.0043 (18)	0.014 (7)	0.013 (6)
C2	0.037 (3)	0.029 (2)	0.039 (18)	0.003 (2)	0.012 (7)	−0.002 (7)
C7	0.030 (3)	0.034 (2)	0.04 (2)	−0.005 (2)	0.005 (7)	−0.003 (7)
C5	0.032 (3)	0.032 (2)	0.032 (19)	0.0026 (19)	0.005 (8)	−0.009 (7)
C6	0.036 (3)	0.039 (3)	0.039 (19)	−0.0039 (18)	0.015 (7)	0.013 (6)
C3	0.037 (2)	0.035 (2)	0.029 (18)	−0.0038 (17)	0.014 (6)	−0.005 (6)
C8	0.030 (3)	0.044 (2)	0.027 (19)	0.0024 (19)	0.013 (6)	−0.001 (7)
C1	0.029 (2)	0.037 (2)	0.042 (19)	−0.001 (2)	0.004 (7)	0.020 (7)
C9	0.041 (3)	0.059 (3)	0.02 (3)	−0.008 (2)	−0.001 (8)	0.000 (8)

Geometric parameters (Å, º)

O2—C7	1.322 (19)	C5—H5	0.9300
O2—C8	1.446 (12)	C5—C6	1.373 (12)
O1—C7	1.221 (10)	C6—H6	0.9300
N1—H1A	0.8576	C6—C1	1.379 (12)
N1—H1B	0.8535	C3—H3	0.9300
N1—C1	1.396 (12)	C8—H8A	0.9700
C4—C7	1.447 (12)	C8—H8B	0.9700
C4—C5	1.41 (2)	C8—C9	1.53 (2)
C4—C3	1.375 (10)	C9—H9A	0.9600
C2—H2	0.9300	C9—H9B	0.9600
C2—C3	1.375 (11)	C9—H9C	0.9600
C2—C1	1.40 (2)
C7—O2—C8	116.6 (6)	C4—C3—C2	122.6 (11)
H1A—N1—H1B	109.3	C4—C3—H3	118.7
C1—N1—H1A	108.5	C2—C3—H3	118.7
C1—N1—H1B	109.3	O2—C8—H8A	110.4
C5—C4—C7	118.6 (8)	O2—C8—H8B	110.4
C3—C4—C7	124.5 (12)	O2—C8—C9	106.7 (6)
C3—C4—C5	116.8 (8)	H8A—C8—H8B	108.6
C3—C2—H2	120.0	C9—C8—H8A	110.4
C3—C2—C1	119.9 (8)	C9—C8—H8B	110.4
C1—C2—H2	120.0	N1—C1—C2	121.1 (10)
O2—C7—C4	112.6 (8)	C6—C1—N1	120.9 (14)
O1—C7—O2	121.9 (11)	C6—C1—C2	118.0 (8)
O1—C7—C4	125.5 (15)	C8—C9—H9A	109.5
C4—C5—H5	119.5	C8—C9—H9B	109.5
C6—C5—C4	121.0 (9)	C8—C9—H9C	109.5
C6—C5—H5	119.5	H9A—C9—H9B	109.5
C5—C6—H6	119.3	H9A—C9—H9C	109.5
C5—C6—C1	121.4 (13)	H9B—C9—H9C	109.5
C1—C6—H6	119.3

4-aminobenzoic acid ethyl ester (BZC_b1)

Crystal data

C9H11NO2	F(000) = 352
Mr = 165.19	Dx = 1.275 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.171 (13) Å	Cell parameters from 704 reflections
b = 5.3995 (9) Å	θ = 3.9–19.5°
c = 19.515 (3) Å	µ = 0.09 mm^−1
β = 92.00 (4)°	T = 298 K
V = 860.4 (14) Å^3	Plate, colourless
Z = 4	0.34 × 0.29 × 0.1 mm

Data collection

Xcalibur, Eos diffractometer	462 independent reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	228 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.069
Detector resolution: 16.1544 pixels mm^-1	θmax = 26.9°, θmin = 3.9°
ω and φ scans	h = −2→2
Absorption correction: multi-scan CrysAlisPro 1.171.38.41 (Rigaku Oxford Diffraction, 2015) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −6→6
Tmin = 0.526, Tmax = 1.000	l = −24→24
3571 measured reflections

Refinement

Refinement on F^2	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.087	H-atom parameters constrained
wR(F^2) = 0.277	w = 1/[σ^2(Fo^2) + (0.1481P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.10	(Δ/σ)max < 0.001
462 reflections	Δρmax = 0.14 e Å^−3
99 parameters	Δρmin = −0.15 e Å^−3
133 restraints

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.222 (3)	0.4071 (13)	0.1341 (4)	0.104 (14)
O2	0.368 (2)	0.6836 (10)	0.0748 (3)	0.107 (6)
N1	0.972 (3)	0.1295 (11)	0.2035 (4)	0.104 (15)
H1A	1.0479	0.1668	0.1745	0.125*
H1B	0.9735	−0.0328	0.2080	0.125*
C4	0.5207 (16)	0.3999 (9)	0.1405 (3)	0.086 (7)
C3	0.6624 (17)	0.5218 (8)	0.1219 (2)	0.087 (7)
H3	0.6551	0.6642	0.0952	0.104*
C2	0.8148 (16)	0.4307 (10)	0.1433 (3)	0.091 (7)
H2	0.9096	0.5122	0.1309	0.109*
C1	0.8257 (16)	0.2178 (11)	0.1832 (3)	0.087 (7)
C6	0.6841 (16)	0.0959 (8)	0.2018 (2)	0.090 (7)
H6	0.6914	−0.0466	0.2285	0.108*
C5	0.5316 (16)	0.1870 (8)	0.1804 (3)	0.086 (7)
H5	0.4369	0.1054	0.1928	0.104*
C7	0.354 (3)	0.490 (2)	0.1176 (6)	0.091 (7)
C9	0.245 (3)	0.9909 (14)	−0.0004 (4)	0.131 (11)
H9A	0.2915	0.9206	−0.0404	0.197*
H9B	0.3207	1.1064	0.0205	0.197*
H9C	0.1449	1.0751	−0.0132	0.197*
C8	0.209 (3)	0.7854 (17)	0.0505 (5)	0.111 (7)
H8A	0.1496	0.8510	0.0887	0.133*
H8B	0.1430	0.6571	0.0284	0.133*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.13 (5)	0.108 (6)	0.080 (5)	0.015 (8)	0.010 (11)	0.017 (3)
O2	0.14 (2)	0.086 (4)	0.090 (4)	0.016 (5)	0.005 (7)	0.009 (3)
N1	0.15 (5)	0.077 (5)	0.091 (6)	−0.008 (8)	0.028 (10)	0.010 (3)
C4	0.133 (19)	0.064 (5)	0.060 (4)	0.011 (7)	−0.004 (8)	0.001 (3)
C3	0.13 (2)	0.063 (4)	0.065 (4)	0.012 (7)	0.003 (9)	0.000 (3)
C2	0.13 (2)	0.076 (5)	0.067 (4)	0.011 (7)	0.012 (9)	0.000 (3)
C1	0.13 (2)	0.067 (5)	0.067 (5)	0.014 (8)	0.007 (9)	−0.006 (4)
C6	0.13 (2)	0.073 (5)	0.065 (4)	0.008 (7)	0.009 (9)	0.001 (3)
C5	0.13 (2)	0.066 (4)	0.060 (4)	−0.001 (6)	0.000 (8)	0.000 (3)
C7	0.137 (19)	0.077 (6)	0.061 (6)	0.009 (7)	0.007 (9)	−0.003 (4)
C9	0.22 (3)	0.084 (5)	0.092 (6)	0.017 (7)	−0.016 (13)	0.012 (4)
C8	0.15 (2)	0.085 (5)	0.099 (6)	0.011 (7)	0.001 (9)	−0.002 (5)

Geometric parameters (Å, º)

O1—C7	1.22 (3)	C2—C1	1.3900
O2—C7	1.346 (14)	C1—C6	1.3900
O2—C8	1.47 (3)	C6—H6	0.9300
N1—H1A	0.8792	C6—C5	1.3900
N1—H1B	0.8807	C5—H5	0.9300
N1—C1	1.330 (19)	C9—H9A	0.9600
C4—C3	1.3900	C9—H9B	0.9600
C4—C5	1.3900	C9—H9C	0.9600
C4—C7	1.501 (19)	C9—C8	1.524 (12)
C3—H3	0.9300	C8—H8A	0.9700
C3—C2	1.3900	C8—H8B	0.9700
C2—H2	0.9300
C7—O2—C8	113.4 (18)	C4—C5—H5	120.0
H1A—N1—H1B	106.3	C6—C5—C4	120.0
C1—N1—H1A	112.0	C6—C5—H5	120.0
C1—N1—H1B	113.5	O1—C7—O2	122.9 (19)
C3—C4—C5	120.0	O1—C7—C4	127.3 (12)
C3—C4—C7	121.7 (7)	O2—C7—C4	109.8 (16)
C5—C4—C7	118.3 (7)	H9A—C9—H9B	109.5
C4—C3—H3	120.0	H9A—C9—H9C	109.5
C4—C3—C2	120.0	H9B—C9—H9C	109.5
C2—C3—H3	120.0	C8—C9—H9A	109.5
C3—C2—H2	120.0	C8—C9—H9B	109.5
C3—C2—C1	120.0	C8—C9—H9C	109.5
C1—C2—H2	120.0	O2—C8—C9	107.1 (17)
N1—C1—C2	120.1 (7)	O2—C8—H8A	110.3
N1—C1—C6	119.9 (7)	O2—C8—H8B	110.3
C2—C1—C6	120.0	C9—C8—H8A	110.3
C1—C6—H6	120.0	C9—C8—H8B	110.3
C5—C6—C1	120.0	H8A—C8—H8B	108.5
C5—C6—H6	120.0

4-aminobenzoic acid ethyl ester (BZC_b2)

Crystal data

C9H11NO2	F(000) = 352
Mr = 165.19	Dx = 1.354 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 6.3608 (8) Å	Cell parameters from 667 reflections
b = 5.1830 (7) Å	θ = 3.2–21.3°
c = 24.75 (5) Å	µ = 0.10 mm^−1
β = 96.66 (5)°	T = 298 K
V = 810.4 (17) Å^3	Plate, colourless
Z = 4	0.34 × 0.31 × 0.1 mm

Data collection

Xcalibur, Eos diffractometer	396 independent reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	197 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.146
Detector resolution: 16.1544 pixels mm^-1	θmax = 27.0°, θmin = 3.2°
ω and φ scans	h = −8→8
Absorption correction: multi-scan CrysAlisPro 1.171.38.41 (Rigaku Oxford Diffraction, 2015) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −6→6
Tmin = 0.606, Tmax = 1.000	l = −6→6
3446 measured reflections

Refinement

Refinement on F^2	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.091	H-atom parameters constrained
wR(F^2) = 0.260	w = 1/[σ^2(Fo^2) + (0.125P)^2 + 0.275P] where P = (Fo^2 + 2Fc^2)/3
S = 1.16	(Δ/σ)max < 0.001
396 reflections	Δρmax = 0.17 e Å^−3
99 parameters	Δρmin = −0.17 e Å^−3
141 restraints

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.0199 (8)	1.1797 (11)	0.1328 (10)	0.077 (9)
O2	0.0077 (9)	0.8470 (11)	0.0754 (9)	0.067 (5)
N1	0.9002 (11)	0.6224 (16)	0.2044 (13)	0.082 (19)
H1A	0.9401	0.4997	0.1843	0.098*
H1B	0.8934	0.5652	0.2369	0.098*
C4	0.3037 (7)	0.8806 (11)	0.1415 (6)	0.061 (6)
C5	0.4173 (9)	1.0132 (11)	0.1841 (6)	0.064 (6)
H5	0.3606	1.1610	0.1981	0.077*
C6	0.6156 (9)	0.9250 (11)	0.2059 (5)	0.071 (7)
H6	0.6915	1.0138	0.2344	0.085*
C1	0.7002 (7)	0.7042 (11)	0.1850 (5)	0.066 (7)
C2	0.5867 (8)	0.5715 (9)	0.1424 (5)	0.064 (7)
H2	0.6433	0.4237	0.1284	0.077*
C3	0.3884 (8)	0.6597 (10)	0.1206 (5)	0.063 (6)
H3	0.3124	0.5709	0.0920	0.076*
C7	0.0988 (10)	0.988 (2)	0.1146 (8)	0.061 (5)
C8	−0.1926 (12)	0.9395 (16)	0.0499 (13)	0.065 (6)
H8A	−0.1754	1.1031	0.0319	0.079*
H8B	−0.2911	0.9625	0.0767	0.079*
C9	−0.2712 (15)	0.737 (2)	0.0094 (14)	0.087 (12)
H9A	−0.1721	0.7171	−0.0168	0.130*
H9B	−0.4061	0.7883	−0.0089	0.130*
H9C	−0.2858	0.5762	0.0278	0.130*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.060 (4)	0.067 (4)	0.10 (3)	0.011 (3)	−0.003 (9)	−0.006 (8)
O2	0.049 (3)	0.070 (3)	0.078 (13)	0.002 (3)	−0.013 (6)	−0.003 (6)
N1	0.063 (5)	0.080 (5)	0.11 (6)	0.018 (4)	0.022 (13)	0.025 (12)
C4	0.051 (4)	0.054 (4)	0.080 (17)	0.000 (3)	0.021 (8)	0.001 (7)
C5	0.055 (4)	0.056 (4)	0.083 (19)	0.003 (3)	0.013 (8)	0.009 (8)
C6	0.064 (4)	0.063 (4)	0.09 (2)	−0.004 (3)	0.013 (8)	0.008 (8)
C1	0.054 (4)	0.058 (4)	0.09 (2)	−0.001 (3)	0.012 (9)	0.002 (8)
C2	0.056 (4)	0.054 (4)	0.08 (2)	0.005 (3)	0.022 (9)	−0.013 (8)
C3	0.055 (4)	0.055 (4)	0.082 (19)	−0.003 (3)	0.022 (8)	−0.012 (7)
C7	0.046 (4)	0.059 (4)	0.078 (15)	−0.002 (4)	0.007 (8)	0.006 (8)
C8	0.043 (4)	0.073 (5)	0.078 (17)	0.002 (4)	0.000 (9)	−0.009 (9)
C9	0.068 (6)	0.090 (6)	0.10 (4)	−0.017 (5)	−0.003 (14)	−0.013 (13)

Geometric parameters (Å, º)

O1—C7	1.222 (16)	C6—C1	1.3900
O2—C7	1.30 (2)	C1—C2	1.3900
O2—C8	1.436 (17)	C2—H2	0.9300
N1—H1A	0.8644	C2—C3	1.3900
N1—H1B	0.8614	C3—H3	0.9300
N1—C1	1.374 (13)	C8—H8A	0.9700
C4—C5	1.3900	C8—H8B	0.9700
C4—C3	1.3900	C8—C9	1.50 (3)
C4—C7	1.500 (2)	C9—H9A	0.9600
C5—H5	0.9300	C9—H9B	0.9600
C5—C6	1.3900	C9—H9C	0.9600
C6—H6	0.9300
C7—O2—C8	115.9 (10)	C4—C3—H3	120.0
H1A—N1—H1B	109.6	C2—C3—C4	120.0
C1—N1—H1A	110.3	C2—C3—H3	120.0
C1—N1—H1B	106.7	O1—C7—O2	124.6 (9)
C5—C4—C3	120.0	O1—C7—C4	120.8 (14)
C5—C4—C7	120.0 (7)	O2—C7—C4	114.3 (10)
C3—C4—C7	119.7 (7)	O2—C8—H8A	110.6
C4—C5—H5	120.0	O2—C8—H8B	110.6
C4—C5—C6	120.0	O2—C8—C9	105.7 (10)
C6—C5—H5	120.0	H8A—C8—H8B	108.7
C5—C6—H6	120.0	C9—C8—H8A	110.6
C1—C6—C5	120.0	C9—C8—H8B	110.6
C1—C6—H6	120.0	C8—C9—H9A	109.5
N1—C1—C6	120.5 (11)	C8—C9—H9B	109.5
N1—C1—C2	119.4 (11)	C8—C9—H9C	109.5
C6—C1—C2	120.0	H9A—C9—H9B	109.5
C1—C2—H2	120.0	H9A—C9—H9C	109.5
C3—C2—C1	120.0	H9B—C9—H9C	109.5
C3—C2—H2	120.0

4-aminobenzoic acid ethyl ester (BZC_b3)

Crystal data

C9H11NO2	F(000) = 352
Mr = 165.19	Dx = 1.356 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 6.3399 (8) Å	Cell parameters from 1183 reflections
b = 5.1789 (6) Å	θ = 3.2–26.2°
c = 24.80 (7) Å	µ = 0.10 mm^−1
β = 96.58 (6)°	T = 298 K
V = 809 (2) Å^3	Plate, colourless
Z = 4	0.47 × 0.31 × 0.1 mm

Data collection

Xcalibur, Eos diffractometer	328 independent reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	209 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.118
Detector resolution: 8.0772 pixels mm^-1	θmax = 25.9°, θmin = 3.2°
ω and φ scans	h = −7→7
Absorption correction: multi-scan CrysAlisPro 1.171.38.41 (Rigaku Oxford Diffraction, 2015) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −6→6
Tmin = 0.415, Tmax = 1.000	l = −6→6
2846 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.093	H-atom parameters constrained
wR(F^2) = 0.280	w = 1/[σ^2(Fo^2) + (0.164P)^2 + 0.695P] where P = (Fo^2 + 2Fc^2)/3
S = 1.16	(Δ/σ)max < 0.001
328 reflections	Δρmax = 0.18 e Å^−3
99 parameters	Δρmin = −0.14 e Å^−3
134 restraints

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.0201 (9)	1.1775 (12)	0.1332 (12)	0.085 (11)
O2	0.0096 (10)	0.8475 (13)	0.0772 (10)	0.080 (9)
N1	0.8999 (11)	0.6219 (15)	0.2049 (14)	0.060 (9)
H1A	0.9423	0.5084	0.1831	0.072*
H1B	0.8941	0.5521	0.2364	0.072*
C4	0.3060 (8)	0.8825 (11)	0.1428 (6)	0.059 (9)
C5	0.4199 (9)	1.0134 (11)	0.1856 (6)	0.061 (9)
H5	0.3638	1.1618	0.1996	0.073*
C6	0.6176 (10)	0.9225 (12)	0.2075 (6)	0.067 (9)
H6	0.6937	1.0101	0.2362	0.080*
C1	0.7014 (8)	0.7008 (11)	0.1867 (6)	0.063 (9)
C2	0.5875 (8)	0.5699 (10)	0.1439 (6)	0.061 (9)
H2	0.6436	0.4216	0.1299	0.073*
C3	0.3898 (8)	0.6608 (11)	0.1219 (6)	0.064 (9)
H3	0.3137	0.5732	0.0933	0.076*
C7	0.0998 (11)	0.9916 (19)	0.1168 (8)	0.075 (10)
C8	−0.1959 (13)	0.9394 (17)	0.0463 (12)	0.079 (10)
H8A	−0.3004	0.9728	0.0711	0.094*
H8B	−0.1727	1.0976	0.0269	0.094*
C9	−0.2717 (17)	0.731 (2)	0.0075 (17)	0.101 (12)
H9A	−0.1570	0.6759	−0.0119	0.151*
H9B	−0.3855	0.7957	−0.0178	0.151*
H9C	−0.3213	0.5878	0.0271	0.151*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.053 (4)	0.058 (3)	0.14 (3)	0.005 (3)	0.003 (11)	−0.026 (9)
O2	0.043 (4)	0.062 (4)	0.13 (3)	0.004 (3)	0.002 (8)	−0.024 (7)
N1	0.052 (4)	0.070 (4)	0.06 (3)	0.021 (3)	0.024 (11)	0.051 (11)
C4	0.039 (5)	0.058 (5)	0.09 (3)	0.005 (3)	0.034 (11)	0.003 (10)
C5	0.045 (5)	0.051 (4)	0.09 (3)	−0.002 (3)	0.012 (11)	0.018 (10)
C6	0.055 (5)	0.061 (5)	0.09 (3)	−0.003 (4)	0.043 (10)	0.021 (11)
C1	0.045 (4)	0.059 (5)	0.09 (3)	−0.001 (4)	0.018 (10)	0.005 (11)
C2	0.049 (5)	0.049 (4)	0.09 (3)	0.004 (4)	0.026 (11)	0.006 (11)
C3	0.051 (5)	0.053 (5)	0.09 (3)	−0.002 (3)	0.026 (11)	0.001 (10)
C7	0.040 (4)	0.055 (5)	0.13 (3)	−0.003 (4)	0.010 (10)	−0.025 (10)
C8	0.044 (4)	0.062 (5)	0.13 (3)	0.001 (4)	0.022 (9)	−0.029 (9)
C9	0.056 (5)	0.093 (7)	0.15 (4)	−0.014 (5)	0.009 (14)	−0.012 (14)

Geometric parameters (Å, º)

O1—C7	1.181 (17)	C4—C7	1.500 (3)
O2—C7	1.31 (2)	C5—C6	1.3900
O2—C8	1.51 (2)	C6—C1	1.3900
N1—C1	1.351 (14)	C1—C2	1.3900
C4—C5	1.3900	C2—C3	1.3900
C4—C3	1.3900	C8—C9	1.49 (3)
C7—O2—C8	118.5 (9)	C6—C1—C2	120.0
C5—C4—C3	120.0	C3—C2—C1	120.0
C5—C4—C7	119.7 (7)	C2—C3—C4	120.0
C3—C4—C7	120.2 (7)	O1—C7—O2	123.7 (11)
C6—C5—C4	120.0	O1—C7—C4	123.0 (15)
C5—C6—C1	120.0	O2—C7—C4	113.0 (9)
N1—C1—C6	120.4 (12)	C9—C8—O2	107.2 (10)
N1—C1—C2	119.4 (12)