Quantitative investigation of C-H?π and other intermolecular interactions in a series of crystalline: N -(substituted phenyl)-2-naphthamide derivatives

Article abstract of DOI:10.1039/c7ce01310h

In this study, we have investigated the nature and characteristics of different intermolecular interactions present in a series of seven N-(substituted phenyl)-2-naphthamides. The seven structures comprise 2-naphthyl ring systems linked by amide bridges to N-bound phenyl 1, or substituted benzene rings 3-7, or in the case of 2, a cyclohexane ring. A common feature of the crystal packing for all but the o-nitro derivative 7 is the presence of a strong intermolecular N-H?O interaction. In the case of 7, the possibility of such an interaction is obviated by the formation of an intramolecular N-H?O hydrogen bond. An additional feature of the crystal packing for 1-6 is the significant roles that C-H?π contacts play in generating three-dimensional networks. In contrast for 7, the intramolecular N-H?O hydrogen bond precludes the formation of molecular chains but the planar nature of this molecule allows significant π?π stacking interactions to stabilize the packing.

Full text of DOI:10.1039/c7ce01310h

View Article Online
View Journal
CrystEngComm
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: R. shukla, A.
Saeed, J. Simpson and D. Chopra, CrystEngComm, 2017, DOI: 10.1039/C7CE01310H.
This is an Accepted Manuscript, which has been through the
Volume 18 Number 1 7 January 2016 Pages 1–184
Royal Society of Chemistry peer review process and has been
accepted for publication.
CrystEngComm
Accepted Manuscripts are published online shortly after
www.rsc.org/crystengcomm
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
HIGHLIGHT
Tiddo J. Mooibroek, Antonio Frontera et al.
Towards design strategies for anion–π interactions in crystal engineering
event shall the Royal Society of Chemistry be held responsible
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
rsc.li/crystengcomm

Page 1 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
Quantitative investigation of CꢀH···π and other intermolecular interactions in a
series of crystalline Nꢀ(substituted phenyl)ꢀ2ꢀnaphthamide derivatives.
Rahul Shuklaa, Aamer Saeed*b, Jim Simpson*c and Deepak Chopra*a
a Crystallography and Crystal Chemistry Laboratory, Department of Chemistry,
IISER Bhopal, Bhopal 462066, Madhya Pradesh, India.
E-mail: dchopra@iiserb.ac.in; Tel: +91 0755 669 1311
b Department of Chemistry, Quaid-i-Azam University-45320, Islamabad, Pakistan
E-mail aamersaeed@yahoo.com Fax +9251 9064 2241; Tel +9251 9064 2128
c Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
E-mail: jsimpson@alkali.otago.ac.nz; Fax +643 479 7906; Tel: +643 479 7914
Abstract
In this study, we have investigated the nature and characteristics of different intermolecular
interactions present in a series of seven Nꢀ(substituted phenyl)ꢀ2ꢀnaphthamides. The seven
structures comprise 2ꢀnaphthyl ring systems linked by amide bridges to Nꢀbound phenyl, 1,
or substituted benzene rings
3
ꢀ7
, or in the case of
2, a cyclohexane ring. A common feature of
the crystal packing for all but the
oꢀnitro derivative 7 is the presence of a strong
intermolecular NꢀH···O interaction. In case of
obviated by the formation of an intramolecular NꢀH···O hydrogen bond. An additional
feature of the crystal packing for is the significant roles that C—H···π contacts play in
generating three dimensional networks. In contrast for , the intramolecular N—H···
7, the possibility of such an interaction is
1—6
7
O
hydrogen bond precludes the formation of molecular chains but the planar nature of this
molecule allows significant π···π stacking interactions to stabilize the packing.
Introduction
Understanding the role of intermolecular interaction and their contribution to molecular packing is
one of the very important aspects of crystal engineering.1ꢀ5 Intermolecular interactions also play very
important roles in both chemistry6ꢀ9 and biology.10ꢀ13 The fact that intermolecular interactions can be
used very efficiently to design new materials with desirable properties14ꢀ16 has attracted immense
attention from the scientific community. Hydrogen bonds are one of the most studied intermolecular
interactions. These are defined as “an attractive interaction between a hydrogen atom from a
molecule or a molecular fragment X–H in which X is more electronegative than H, and an atom or a
group of atoms in the same or a different molecule, in which there is evidence of bond formation”.17ꢀ
18 While strong hydrogen bonds such as N/OꢀH···O/N19ꢀ20 are well recognized and characterized, the
focus in the past decade has shifted to investigations of role of weak hydrogen bonds such as such as
CꢀH···X (X = O, N, S, halogens and πꢀelectrons)21ꢀ34 in molecular crystals. Among these weak

CrystEngComm
Page 2 of 35
View Article Online
DOI: 10.1039/C7CE01310H
hydrogen bonds, CꢀH···π interactions have garnered significant attention due to their unique features
and characteristics. Some consider these contacts to be in the grey area between hydrogen bonds and
van der Waals interactions rather than pure hydrogen bonds.35 Another interesting feature of the Cꢀ
H···π interaction is that it is mainly dispersive in nature36ꢀ40 as opposed to traditional hydrogen bonds
which are largely considered to be electrostatic interactions.41ꢀ42 Regardless of the nature of the
contacts, CꢀH···π interactions have established themselves as important interacting forces because
of their role not only in molecular crystals31,34,43ꢀ46 but also in several other areas including chiral
recognition47ꢀ48, polymer chemistry,49ꢀ50 coordination chemistry,51ꢀ52 biochemistry,53ꢀ54 and the
structures of DNA55ꢀ56 and proteins.57ꢀ58 Several theoretical studies on model complexes have also
been performed in order to understand these interactions from a quantitative point of view.59ꢀ60
Therefore, a systematic investigate of the role of attractive CꢀH···π interactions alongside other
intermolecular interactions is desirable.
In this study we have synthesized a series of seven Nꢀsubstituted 2ꢀnaphthamide derivatives. Of
the seven derivatives reported here, the 2ꢀnapthamide substituents include Nꢀbound phenyl,
1,
cyclohexyl, , and five substituted benzene rings, . Napathamide derivatives are an
2
3ꢀ7
important class of compound which exhibit a range of biological functions. These include use
in in vitro studies,61 as kinase inhibitors,62 in the determination of binding affinities,63 as
antipsychotic agents64 and in the treatment of Alzheimer's disease.65 In view of these important
applications, it is of interest to systematically and quantitatively explore the molecular geometry and
intermolecular interactions that are involved in the formation of crystals of this class of molecules.
The recent emergence of a variety of computational tools such as PIXEL, XPAC2.0 and Crystal
Explorer will assist in the quantitative investigation of CꢀH···π and other intermolecular interactions
present in the crystal structures of the molecules reported here.
Experimental Section
Synthesis of Nꢀ(substituted phenyl)ꢀ2ꢀnaphthamides (1—7)
The Nꢀ(substituted phenyl)ꢀ2ꢀnaphthamides (1ꢀ7) were synthesized in
a
single step
carbonyldiimidazole promoted process shown in Scheme 1, which was originally developed for the
oneꢀpot synthesis of N,Nꢀdisubstituted anilines.66 2ꢀNaphthoic acid (10 mmol) was added slowly
with stirring to a solution of carbonyldiimidazole (CDI) (10 mmol) dissolved in 30 mL dry THF at
room temperature under nitrogen atmosphere. The reaction mixture was further stirred for 15 min
and a solution of the appropriate aniline (10 mmol) in 30 mL dry THF was added slowly. The

Page 3 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
stirring was continued for an additional 10 min at room temperature then the mixture refluxed for 3
h. After completion of the reaction, monitored by TLC, the reaction mixture was concentrated to
obtain the crude products in 76—91% yields as white solids. Colourless crystals were obtained in
each case on slow evaporation from a methanol solution.
O
CDI / dry THF
OH
H2N
R
relux
O
R
N
H
Scheme 1. Synthesis of Nꢀphenylꢀ2ꢀnaphthamide derivatives. R = C6H5, 1; C6H11, 2; 3ꢀCH3ꢀC6H5, 3;
4ꢀClꢀC6H5, 4; 3ꢀCH3OꢀC6H5, 5; 4ꢀCH3OC6H5, 6 and 2ꢀO2NꢀC6H5, 7.
NꢀPhenylꢀ2ꢀnaphthamide, 1
Yield: 77 %; m.p: 185°C; IR (pure, cmꢀ1): 3262 (NꢀH), 3066 (Csp2ꢀH), 1674 (CONH), 1588 (C=C,
Ar), 1HꢀNMR (300MHz, DMSOꢀd6): δ 8.51 (s, 1H, NH), 8.22ꢀ8.13 (m, 2H, ArꢀH), 8.09ꢀ8.04 (m, 2H,
ArꢀH), 7.86ꢀ7.83 (m, 1H, ArꢀH), 7.75ꢀ7.59 (m, 4H, ArꢀH), 7.52ꢀ7.49 (m, 3H, ArꢀH); 13CꢀNMR (75.4
MHz, DMSOꢀd6): δ 180.7, 155.92, 133.4, 132.2, 131.5, 129.9, 129.03 127.9, 127.7, 127.0, 126.4,
125.17 119.8; Anal. Calcd. For C17 H13 N O: C, 82.57; H, 5.30; N, 5.66; Found: C, 82.61; H, 5.29; N,
5.68; GCꢀMS m/z: 247.02, (M·+).
NꢀCyclohexylꢀ2ꢀnaphthamide, 2
Yield: 74 %; m.p: 176°C; IR (pure, cmꢀ1): 3271 (NꢀH), 3060 (Csp2ꢀH), 2926 (CH2), 1641 (CONH),
1
1586 (C=C, Ar), 1641 (CONH), HꢀNMR (300MHz, DMSOꢀd6): δ 8.22ꢀ8.13 (m, 2H, ArꢀH), 8.09ꢀ
8.04 (m, 2H, ArꢀH), 7.86ꢀ7.83 (m, 1H, ArꢀH), 7.75ꢀ7.59 (m, 2H, ArꢀH), 1.18ꢀ1.45 (4H, m, CH2 x 2),
1.60ꢀ1.76 (4H, m, CH2 x 2), 1.94ꢀ2.02 (2H, dd, CH2 ), 3.94 (1H, m, CH); 13CꢀNMR (75.4 MHz,
DMSOꢀd6): δ 180.7, 133.4, 132.2, 131.5, 129.9, 129.03 127.9, 127.7, 127.0, 126.4, 25.81 (CH2ꢀ4
cycl), 24.75 (CH2ꢀ3), 33.03 (CH2ꢀ2), 53.71 (CH); Anal. Calcd. For C17 H19 N O: C, 80.60; H, 7.56;
N, 5.53; Found: C, 80.56; H, 7.61; N, 5.57; GCꢀMS m/z: 253.15, (M·+).
Nꢀ(mꢀTolyl)ꢀ2ꢀnaphthamide, 3
Yield: 81 %; m.p: 192°C; IR (pure, cmꢀ1): 3271 (NꢀH), 3063 (Csp2ꢀH), 1675 (CONH), 1587 (C=C,
Ar), 1HꢀNMR 300MHz, DMSOꢀd6): δ 7.91 (s, 1H, NH), 8.25ꢀ8.23 (d, 1H, J=8.1 Hz, ArꢀH), 8.14 (d,
1H, J=8.1 Hz, ArꢀH), 8.06ꢀ8.01 (m, 2H, ArꢀH), 7.88ꢀ7.86 (m, 1H, ArꢀH), 7.70ꢀ7.59 (m, 4H, ArꢀH),

CrystEngComm
Page 4 of 35
View Article Online
DOI: 10.1039/C7CE01310H
7.46 (t, 1H, J=8.1 Hz, ArꢀH), 2.51 (s, 3H, CH3); 13CꢀNMR (75.4 MHz, DMSOꢀd6): δ 161.9, 138.0,
133.5, 132.4, 132.2, 131.4, 129.9, 129.1, 129.0, 128.3, 128.1, 128.0, 127.8, 127.6, Anal. Calcd. For
C18H15NO: C, 82.73; H, 5.79; N, 5.36; Found: C, 82.69; H, 5.81; N, 5.37; GCꢀMS m/z: 261.1, (M·+).
Nꢀ(4ꢀChlorophenyl)ꢀ2ꢀnaphthamide, 4
1
Yield: 83%; m.p: 179°C; IR (pure, cmꢀ1): 3250 (NꢀH), 1668 (CO), 1577 (C=C), 780 (CꢀCl); Hꢀ
NMR 300MHz, DMSOꢀd6): δ 8.4 (s, 1H, NH), 8.3 (d, 1H, J=7.8, ArꢀH), 8.06ꢀ8.02 (m, 2H, ArꢀH),
7.83ꢀ7.79 (m, 3H, ArꢀH), 7.68 (d, 2H, J=8.4, ArꢀH), 7.42 (d, 2H, J=8.4, ArꢀH); 13CꢀNMR (75.4
MHz, DMSOꢀd6): δ 169.3, 170.4, 160.3 137.6, 133.4, 132.0, 131.8, 129.9, 128.9, 127.8, 127.6,
126.9, 125.2; Anal. Calcd. For C17H12 ClNO: C, 72.47; H, 4.29; N, 4.97; Found: C, 72.52; H, 4.31;
N, 4.93; GCꢀMS m/z: 281.0, 283.0 (M·+).
Nꢀ(3ꢀMethoxyphenyl)ꢀ2ꢀnaphthamide, 5
Yield: 89%; m.p: 181°C; IR (pure, cmꢀ1): 3250 (NꢀH), 2950 (CH3), 1668 (CO), 1577 (C=C), 1265
(C=S), 1HꢀNMR 300MHz, DMSOꢀd6): δ 8.03 (s, 1H, NH), 8.13 (d, 1H, J=8.4, ArꢀH), 8.06ꢀ8.02 (m,
1H, ArꢀH), 7.83ꢀ7.79 (m, 2H, ArꢀH), 7.68ꢀ7.58 (m, 3H, ArꢀH), 7.42ꢀ7.31 (m, 2H, ArꢀH), 4.01 (s, 3H,
OCH3); 13CꢀNMR (75.4 MHz, DMSOꢀd6): δ 165.4, 160.3 137.6, 133.4, 132.0, 131.8, 129.9, 128.9,
127.8, 127.6, 126.9, 125.2, 122.7, 56.1 Anal. Calcd. For C18H15NO2: C, 77.96; H, 5.45; N, 4.97;
Found: C, 77.91; H, 5.49; N, 5.07; GCꢀMS m/z: 277.2 (M·+).
Nꢀ(4ꢀMethoxyphenyl)ꢀ2ꢀnaphthamide, 6
Yield: 91%; m.p: 201°C; IR (pure, cmꢀ1): 3250 (NꢀH), 2950 (CH3), 1668 (CO), 1577 (C=C), 1265
(C=S), 1HꢀNMR 300MHz, DMSOꢀd6): δ 8.3 (s, 1H, NH), 7.81 (d, 1H, J=7.8, ArꢀH), 7.79 (d, 1H,
J=8.4, ArꢀH), 7.83ꢀ7.79 (m, 2H, ArꢀH), 7.68ꢀ7.58 (m, 3H, ArꢀH), 7.42ꢀ7.31 (m, 2H, ArꢀH), 3.97 (s,
3H, ArꢀOCH3); 13CꢀNMR (75.4 MHz, DMSOꢀd6): δ 169.5, 170.4, 160.3 137.6, 133.4, 132.0, 131.8,
129.9, 128.9, 127.8, 127.6, 126.9, 125.2, 122.7, 56.2; Anal. Calcd. For C18H15NO2: C, 77.96; H,
5.45; N, 5.05; Found: C, 78.01; H, 5.41; N, 5.09; GCꢀMS m/z: 277.2 (M·+).
Nꢀ(2ꢀNitrophenyl)ꢀ2ꢀnaphthamide, 7
Yield: 76 %; m.p: 189°C; IR (pure, cmꢀ1): 3271 (NꢀH), 3063 (Csp2ꢀH), 1675 (CONH), 1564 (ꢀNO2),
1587 (C=C), 1HꢀNMR 300MHz, DMSOꢀd6): δ 8.70 (s, 1H, NH), 8.33 (m, 4H, ArꢀH), 8.25ꢀ8.23 (d,
1H, J=8.1 Hz, ArꢀH), 8.14 (d, 1H, J=8.1 Hz, ArꢀH), 8.06ꢀ8.01 (m, 2H, ArꢀH), 7.88ꢀ7.86 (m, 1H, Arꢀ
H), 7.70ꢀ7.59 (m, 2H, ArꢀH),; 13CꢀNMR (75.4 MHz, DMSOꢀd6): δ 164.9, 149.92, 138.0, 133.5,
132.4, 132.2, 131.4, 129.9, 129.1, 129.0, 129.58, 128.3, 128.1, 128.0, 127.8, 127.4. Anal. Calcd. For
C17H12N2O3: C, 69.86; H, 4.14; N, 9.58; Found: C, 69.90; H, 4.11; N, 9.60; GCꢀMS m/z: 298.0
(M·+).
Xꢀray structure determinations
Xꢀray measurements for 1—7 were carried out on a Bruker APEXII Kappa CCD single crystal
diffractometer equipped with a graphite monochromator. MoKα radiation (λ = 0.71073 Å) was used

Page 5 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
for all of the collections which were controlled by APEX267 with data collected at 89(2) K. Data
were corrected for Lorentz and polarization effects using SAINT67 and multiꢀscan absorption
corrections were applied using SADABS.67 The structures were solved by direct methods (SHELXSꢀ
97)68 and refined using fullꢀmatrix leastꢀsquares procedures (SHELXLꢀ9768 and Titan200069). All
nonꢀhydrogen atoms were refined anisotropically and all hydrogen atoms bound to carbon were
placed in the calculated positions, and their thermal parameters were refined isotropically with Ueq =
1.2—1.5 Ueq(C). The N—H hydrogen atoms were located in difference Fourier maps and their
coordinates were refined with Ueq = 1.2 Ueq(N). Compound 5 crystallised with two unique but
closely similar molecules, designated A and B, in the unit cell. These overlay with an rms deviation
of 0.1105 Å and the numbering scheme labels atoms with a trailing A or B as appropriate. Two
reflections for 1, one for each of 2, 3, 4 were found to be clearly affected by the beamꢀstop and these
were omitted from the final refinement. Compounds 1, 2 and 5 crystallised in nonꢀcentric space
groups but the absence of a heavy atom meant that the absolute structure could not be reliably
determined. Despite this, Friedel opposites were not merged in the final refinement. All molecular
plots and packing diagrams were drawn using Mercury70 and additional metrical data were calculated
using PLATON.71 Tables were prepared using WINGX.72 Details of the Xꢀray measurements and
crystal data for all of the complexes are given in Table 1.
Table 1 Crystal data and structure refinement of 1ꢀ7
1
2
3
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
a (Å)
C17H13NO
247.28
C17H19NO
253.33
C18H15NO
261.31
89(2)
89(2)
89(2)
0.71073
Monoclinic
C c
0.71073
Monoclinic
P 21
0.71073
Monoclinic
P 21/c
28.7372(16)
5.4797(3)
7.8381(5)
90
5.1820(9)
6.5439(11)
19.416(3)
90
26.362(2)
5.8842(5)
8.6253(7)
90
b (Å)
c (Å)
α (°)
β (°)
γ (°)
104.767(3)
90
92.448(9)
90
92.291(5)
90
V (A3)
1193.51(12)
4
657.81(19)
2
1336.9(2)
4
Z
Dcalc (gcmꢀ3)
µ (mmꢀ1)
1.376
1.279
1.298
0.086
0.079
0.080
F (000)
520
272
552
Crystal size
Theta range for data collection
0.52 x 0.42 x 0.04
4.32 – 31.99
0.38 x 0.18 x 0.13
3.29 – 33.40
0.46 x 0.24 x 0.15
2.32 – 33.16

CrystEngComm
Page 6 of 35
View Article Online
DOI: 10.1039/C7CE01310H
Reflections collected
independent
10441
10572
22348
3533 [R(int) = 0.0380]
3049
4420 [R(int)= 0.0309]
4687 [R(int)= 0.0545]
3578
observed
3873
Min. and max. transmission
Data/restraints/parameters
Goodnessꢀofꢀfit
1.0000, 0.7968
1.0000, 0,8339
1.0000, 0.7414
3533 / 2 / 175
4420/1/175
4687/0/185
1.043
1.090
1.084
Final R indices [I >2σ(I)]
R indices (all data)
R1 = 0.0445, wR2 = 0.1103
R1 = 0.0529, wR2 = 0.1152
R1 = 0.0486, wR2 = 0.1417
R1 = 0.0628, wR2 = 0.1692
0.652 and ꢀ0.489
R1 = 0.0895, wR2 = 0.2443
R1 = 0.1086, wR2 = 0.2550
0.790 and ꢀ0.468
Largest difference peak and 0.409 and ꢀ0.231
hole (e Åꢀ3)
CCDC reference number
997577
997578
997579

Page 7 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
4
5
6
Empirical formula
C17H12NOCl
281.73
C18H15NO2
277.31
C18H15NO2
277.31
Formula weight
Temperature (K)
89(2)
89(2)
89(2)
Wavelength (Å)
0.71073
Triclinic
P ꢀ1
0.71073
Orthorhombic
P 212121
9.7762(5)
11.4779(5)
24.3526(11)
90
0.71073
Triclinic
P ꢀ1
Crystal system
Space group
a (Å)
5.5994(11)
7.4730(15)
15.867(3)
88.78(3)
84.12(3)
84.82(3)
657.7(2)
2
5.5162(6)
7.4987(7)
16.1006(17)
86.535(3)
87.169(4)
86.154(4)
662.59(12)
2
b (Å)
c (Å)
α (°)
β (°)
γ (°)
90
90
V (A3)
2732.6(2)
8
Z
Dcalc (gcmꢀ3)
1.423
1.348
1.390
µ (mmꢀ1)
0.284
0.088
0.091
F (000)
292
1168
292
Crystal size
0.48 x 0.25 x 0.13
3.01 – 33.29
12246
0.66 x 0.30 x 0.19
1.67 – 33.44
51581
0.58 x 0.25 x 0.21
1.27 – 33.42
12388
Theta range for data collection
Reflections collected
independent
observed
4495 [R(int) = 0.0306]
3668
9858 [R(int)= 0.0435]
8343
4594 [R(int)= 0.0336]
3658
Min. and max. transmission
Data/restraints/parameters
Goodnessꢀofꢀfit
1.0000, 0.8373
1.0000, 0.8468
1.0000, 0.8205
4495 / 2 / 184
9858/2/387
4594/1/195
1.065
1.043
1.071
Final R indices [I >2σ(I)]
R indices (all data)
R1 = 0.0392, wR2 = 0.1044
R1 = 0.0494, wR2 = 0.1104
R1 = 0.0431, wR2 = 0.1073
R1 = 0.0555, wR2 = 0.1144
0.429 and ꢀ0.220
R1 = 0.0464, wR2 = 0.1374
R1 = 0.0588, wR2 = 0.1534
0.578 and ꢀ0.363
Largest difference peak and 0.479 and ꢀ0.280
hole (e Åꢀ3)
CCDC reference number
997580
997581
997582

CrystEngComm
Page 8 of 35
View Article Online
DOI: 10.1039/C7CE01310H
7
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
a (Å)
C17H12N2O3
292.29
89(2)
0.71073
Triclinic
P ꢀ1
7.2920(6)
8.1868(6)
12.1035(10)
86.710(5)
84.055(5)
65.201(4)
652.32(9)
2
b (Å)
c (Å)
α (°)
β (°)
γ (°)
V (A3)
Z
Dcalc (gcmꢀ3)
µ (mmꢀ1)
1.488
0.104
F (000)
304
Crystal size
Theta range for data collection
Reflections collected
0.52 x 0.26 x 0.04
3.73 – 28.83
9255
independent
observed
3345 [R(int) = 0.0376]
2362
Min. and max. transmission
Data/restraints/parameters
Goodnessꢀofꢀfit
1.0000, 0.8726
3345 / 0 / 202
1.037
Final R indices [I >2σ(I)]
R indices (all data)
R1 = 0.0505, wR2 = 0.1174
R1 = 0.0789, wR2 = 0.1308
Largest difference peak and 0.409 and ꢀ0.231
hole (e Åꢀ3)
CCDC reference number
997585
Theoretical Studies
Lattice energy and intermolecular interaction energies partitioned into coulombic, polarization,
dispersion and repulsion energy terms were evaluated using the PIXEL method present in the CLP
module.73ꢀ75 Similar calculations have been utilized in several related studies.76ꢀ77 Electrostatic
potential maps (MESP) were plotted on the Hirshfeld surface at B3LYP/6ꢀ311G** with potentials
ranging from ꢀ0.06 au (red) to 0.06 au (blue) using Crystal Explorer (version 17.5).78 This program
was also used for mapping 2D fingerprint plots79ꢀ80 to help with evaluating the contribution of the
different intermolecular interactions present in a molecule in a crystalline environment. Analysis of

Page 9 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
similarity and dissimilarity between the reported structures was performed using XPac2.081ꢀ82 which
helps in identifying 0D, 1D, 2D or 3D supramolecular constructs (SC) for a pair of molecule. It also
provides information on the extent of dissimilarity (dissimilarity index ‘x’) as well as the
dissimilarity parameters such as the stretch parameter ‘D’. For XPac analysis, we have taken all of
the atomic coꢀ ordinates (in crystal geometry) of the amide bonds and the rings carbon atoms.
CSD Search
CSD version 5.38 (Nov 2016)83 was used to identify previously reported Nꢀ(substituted phenyl)ꢀ2ꢀ
naphthamide derivatives. Only organic structures whose 3D coordinates are determined and are not
disordered, ionic, polymeric, and have no errors were included in the search. Powder structures were
also excluded from the search together with limiting the search to structures with Rꢀfactors < 0.1.
Result and Discussion
Molecular Structure and Conformation
ORTEP diagrams of all the seven structures are presented in Figure 1. The molecular structure of
each the compounds comprises a planar napathamide ring system linked by a C(=O)NH amide unit
to a phenyl or substituted phenyl ring except in the case of 2 where the second molecular component
is a cyclohexane ring. All the molecules have two kinds of hydrogen bond donors [NꢀH, CꢀH]. The
majority of the CꢀH donors are the C(sp2)_H donors of the aromatic rings while molecules 3, 4, 5
additionally provide C(sp3)ꢀH donors. Oxygen atoms from the O=C and OꢀCH3 groups or the πꢀ
electron clouds of the aromatic rings can act as hydrogen bond acceptors in the various systems. The
presence of πꢀ electron clouds can also result in the π···π stacking interactions being involved in the
crystal packing. The chlorine atom present in 4 can participate, in either hydrogen or a halogen
bonding. With the exception of 5 all of the compounds crystallise with one molecule in the
asymmetric unit. 5 on the other hand has two molecules in the asymmetric unit that are linked by Nꢀ
H···O and CꢀH···O interactions in addition to an offset π···π interaction [Figure 1(e)]. The molecular
conformation of 7 [Figure 1(g)] was stabilized by the formation of an intramolecular NꢀH···O
hydrogen bond [dH…O: 2.00Å ; ∠NꢀH…O: 134°].

CrystEngComm
Page 10 of 35
View Article Online
DOI: 10.1039/C7CE01310H
Figure 1: ORTEP plots for a) 1 b) 2 c) 3 d) 4 e) 5 f) 6 g) 7 with ellipsoids for the nonꢀhydrogen
atoms drawn with the 50% ellipsoidal probability level.
The overlay diagram [Figure 2] of all the structures reveals the considerable conformational
flexibility between these structures. The magnitudes of the three major torsional angles in each of the
structures are shown in Table 2. The magnitude of τ2 representing the torsion about the amide bond
was largely unaffected by the molecular environment, falling in the narrow range of 172ꢀ180°. τ1 and
τ3 had similar magnitudes in case of 1, 2, 4 and 6 with magnitudes ranging from 149ꢀ153° (τ1) and
148ꢀ159 (τ3), respectively. In case of 3 and 5, τ2 was significantly less while τ3 remain unaffected
suggesting the rotation of the molecule via naphthalene ring to give nearly planar molecules. In the
case of 7 however, the magnitudes of the τ3 [21°] and τ1 [168°] angles are reversed in comparison to
those for 3 and 5 but with the molecule remaining reasonable planar, excluding the NO2 substituent.
Here an oxygen atom of the –NO2 group avoids steric hindrance with the O=C group of the amide
bond [Figure 1(g)] and instead stabilizes the molecular structure by forming a strong intramolecular
NꢀH···O hydrogen bond.

Page 11 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
Figure 2: Molecular overlay diagram of the crystal structures of 1ꢀ7 with respective color codes.
Table 2: Magnitude of important torsions τ1, τ2, τ3 in molecules 1ꢀ7.
Code
1
2
3
4
5_A
5_B
6
τ1(N1ꢀC21ꢀC2ꢀC1)
149.0(1)
155.5(1)
26.8(1)
τ2 (C2ꢀC21ꢀN1ꢀC11) τ3(C21ꢀN1ꢀC11ꢀC16)
178.2(1)
178.5(1)
176.1(1)
173.7(5)
179.5(1)
179.8(1)
171.9(1)
177.2(1)
149.6(1)
147.7(1)
156.3(1)
158.6(5)
147.8(1)
150.9(1)
159.0(1)
20.6(1)
153.7(4)
34.4(1)
32.4(1)
153.2(1)
167.9(1)
7

CrystEngComm
Page 12 of 35
View Article Online
DOI: 10.1039/C7CE01310H
Lattice Energy and Electrostatic Potential Maps
Table 3: Lattice Energies of structures 1ꢀ7(kJ/mol).
Code
Ecoul
Epol
Edisp
Erep
Etotal
ꢀ62.4
ꢀ61.2
ꢀ79.2
ꢀ70.5
ꢀ86.5
ꢀ75.3
ꢀ45.1
ꢀ30.7
ꢀ28.4
ꢀ40.7
ꢀ27.7
ꢀ40.7
ꢀ38.6
ꢀ19.6
ꢀ190.7
ꢀ184.0
ꢀ185.9
ꢀ199.5
ꢀ194.7
ꢀ210.6
ꢀ191.0
130.2
129.2
151.6
136.7
156.1
155.1
119.0
ꢀ153.6
ꢀ144.4
ꢀ154.2
ꢀ161.0
ꢀ165.8
ꢀ169.6
ꢀ136.6
1
2
3
4
5
6
7
Table 3 shows the calculated lattice energies for the crystal structures reported here with magnitudes
ranging from ꢀ136.6 kJ/mol (7) to ꢀ169.6 kJ/mol (6). It is clearly evident that presence of a phenyl
ring in (1) provides somewhat more stability to the lattice than a cyclohexane ring in (2). Also, the
presence of different substituents i.e. –CH3 (3) –OCH3 (5, 6) and –Cl (4) substituents results in
relatively large lattice energies. The presence of additional substituents can lead to presence of
additional intermolecular interactions which inturn can lead to additional lattice stability. However in
case of 7, the presence of oꢀNO2 group resulted in decrease in overall lattice energy due to
significantly lower contribution from the Eelec and Epol energy components. The presence of an
intramolecular NꢀH···O interaction can be attributed to this decrease in case of 7. The dispersion
energy was the largest contributor towards the stability of the lattice with percentage contribution
towards stabilization ranging from 60% (5) to 75% (7). [The percentage contribution towards
stabilization was calculated by adding the contribution of individual stabilization components
(coulombic + polarization + dispersion) with the total of stabilization terms]. The largest 40%
contribution towards stabilization obtained from Ecoul and Epol in 5 can be attributed to the presence
of two molecules in the asymmetric unit which can result in more electrostatic driven interactions in
the lattice.
The Molecular Electrostatic Potential (MESP) maps show that the πꢀregion of the naphthalene ring
(in red, marked as region A) [Figure 3] have negative electrostatic regions for all of the molecules
and hence can act as a hydrogen bond acceptors. The phenyl ring (in red, marked as region B) also
displays a negative electrostatic region for all the molecules except 7. In the case of 7, the phenyl
ring carries a strongly electron withdrawing ꢀNO2 substituent resulting in the phenyl ring being
electron deficient [Figure 3(h)]. Also, as expected, the additional hydrogen atoms on the cyclohexane
ring results in the region around this ring having a positive electrostatic region [Figure 3(b)].

Page 13 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H

CrystEngComm
Page 14 of 35
View Article Online
DOI: 10.1039/C7CE01310H
Figure 3: Molecular Electrostatic Potential Maps of a) 1 b) 2 c) 3 d) 4 e) 5_A f) 5_B g) 6 h) 7 drawn
on Hirshfeld isosurfaces with potentials ranging from ꢀ0.06 a.u. (red) to 0.06 a.u. (blue).
Molecular Packing and Interaction Energies
Table 4 presents the intermolecular interactions present in the reported structures along with
geometrical parameters and corresponding interaction energies partitioned into different energy
components. Figures S1ꢀS7 shows the important molecular pairs present in each structure and
Figures 4ꢀ10 represents the molecular packing.
Table 4: List of intermolecular interactions observed in Molecule 1ꢀ7 along with interactions
energies and geometrical parameters.
Centroidꢀ
Centroid
dist. (Å)
Symmetry
Code
Intermolecular
Interactions
Geometrical
Parameters
(Å)/(°)/(°)
Motifs
Ecoul
Epol
Edisp
Erep
Etotal
(kJ/mol)
(kJ/mol)
(kJ/mol)
(kJ/mol)
(kJ/mol)
Molecule 1
I
5.480
4.964
4.613
13.900
ꢀ31.6
ꢀ16.1
ꢀ12.5
ꢀ3.6
ꢀ9.9
ꢀ8.0
ꢀ8.3
ꢀ1.1
ꢀ46.6
ꢀ53.0
ꢀ50.1
ꢀ11.1
36.4
37.6
35.9
7.3
ꢀ51.7
ꢀ39.4
ꢀ34.9
ꢀ8.5
x,ꢀ1+y,z
N1ꢀH1N…O1
2.51/165
2.80/125
C3ꢀH3…O1
Stacking
II
x,ꢀy,0.5+z
x,1ꢀy,ꢀ0.5+z
C4ꢀH4…C1(Cg1)
C15ꢀH15…C13(Cg3)
C16ꢀH16…C11(Cg3)
C13ꢀH13…C14(Cg3)
C1ꢀH1…C4(Cg1)
C8ꢀH8…C5(Cg2)
C7ꢀH7…C14(Cg3)
2.72/153
3.00/154
3.00/117
3.00/120
3.00/156
2.63/148
3.06/116
III
IV
ꢀ0.5+x,0.5ꢀy,ꢀ
0.5+z
V
14.627
14.627
ꢀ0.7
ꢀ1.8
ꢀ1.1
ꢀ1.6
ꢀ9.9
5.3
7.3
ꢀ6.3
ꢀ6.2
ꢀ0.5+x,0.5+y,z
ꢀ0.5+x,ꢀ0.5+y,z
C14ꢀH14…H7ꢀC7
C6ꢀH6…H14ꢀC14
2.62/129/114
2.44/132/117
VI
ꢀ10.1
Molecule 2
I
5.182
6.544
ꢀ37.0
ꢀ9.6
ꢀ15.3
ꢀ5.0
ꢀ50.6
ꢀ46.4
50.4
29.3
ꢀ52.4
ꢀ31.7
xꢀ1,y,z
x,yꢀ1,z
N1ꢀH1N…O1
2.16/160
2.77/128
C21ꢀO1…H16B
Molecular Stacking
C16ꢀH16A…C1(Cg1)
C2(Cg1)…C7(Cg2)
II
2.90/133
3.480

Page 15 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
C8(Cg2)…C21
C3ꢀH3…H7ꢀC7
3.397(4)
III
8.347
ꢀ3.2
ꢀ3.8
ꢀ25.0
15.3
ꢀ16.7
xꢀ1,y+1,z
2.46/127/127
C16ꢀH16A….H1ꢀC1
C6ꢀH6…C5(Cg2)
2.54/110/155
3.04/122
IV
V
10.051
10.669
ꢀ3.5
ꢀ3.0
ꢀ1.5
ꢀ1.1
ꢀ15.2
ꢀ14.2
7.9
9.3
ꢀ12.3
ꢀ9.0
ꢀx+2,yꢀ0.5,ꢀz
2ꢀx,yꢀ0.5,1ꢀz
C12ꢀH12A…H13BꢀC13
C13ꢀH13A…H14BꢀC14
C4ꢀH4…H5ꢀC5
2.62/153/102
2.66/106/153
2.44/129/123
2.66/151/130
2.68/110/129
VI
10.383
11.366
ꢀ2.5
ꢀ2.0
ꢀ2.0
ꢀ0.8
ꢀ13.3
ꢀ12.4
9.2
7.8
ꢀ8.6
ꢀ7.4
1ꢀx,ꢀ0.5+y,ꢀz
1ꢀx,ꢀ0.5+y,1ꢀz
VII
C14ꢀH14B…H14AꢀC14
C14ꢀH14B…H12BꢀC12
Molecule 3
I
4.375
ꢀ58.0
ꢀ24.4
ꢀ68.2
88.9
ꢀ61.7
x,0.5ꢀy,ꢀ0.5+z
N1ꢀH1N…O1
1.93/167
2.51/138
2.63/126
2.89/171
2.93/143
2.91/155
C1ꢀH1…O1
C16ꢀH16…O1
C131ꢀH13B…C15(Cg3)
C12ꢀH12…C16(Cg3)
C8ꢀH8…C4(Cg1)
II
5.884
6.716
7.901
13.988
13.746
ꢀ5.9
ꢀ3.2
ꢀ3.5
ꢀ2.6
ꢀ2.4
ꢀ4.2
ꢀ3.3
ꢀ2.2
ꢀ1.6
ꢀ1.4
ꢀ39.8
ꢀ25.6
ꢀ14.4
ꢀ13.1
ꢀ11.4
20.9
14.2
9.8
ꢀ29.0
ꢀ17.8
ꢀ10.3
ꢀ8.9
x,ꢀ1+y,z
Molecular Stacking
C4ꢀH4…C8(Cg2)
C15ꢀH15…C13(Cg3)
C131ꢀH13A…H14
C5ꢀH5…H6ꢀH7
III
x,1.5ꢀy,0.5+z
x,ꢀ0.5ꢀy,ꢀ0.5+z
ꢀx,ꢀy,2ꢀz
2.93/154
IV
2.95/142
V
8.4
2.51/151
VI
7.0
ꢀ8.2
1ꢀx,0.5+y,1.5ꢀz
2.50/152/118
Molecule 4
I
5.599
ꢀ32.2
ꢀ9.8
ꢀ48.9
37.1
ꢀ53.7
xꢀ1,y,z
N1ꢀH1N…O1
2.53/155
2.65/133
C16ꢀH16…O1
Stacking
II
4.351
4.613
ꢀ16.0
ꢀ17.0
ꢀ7.3
ꢀ8.5
ꢀ58.0
ꢀ57.1
36.6
40.8
ꢀ44.7
ꢀ41.8
1ꢀx,ꢀy,1ꢀz
ꢀx,1ꢀy,1ꢀz
C12ꢀH12…C3(Cg1)
C13ꢀH13…C5(Cg2)
C15ꢀH15…C8(Cg2)
C16ꢀH16…C1(Cg1)
C8ꢀH8…C15(Cg3)
C4ꢀH4…C12(Cg3)
C6ꢀH6…Cl14
2.95/153
2.91/147
2.90/142
2.85/144
2.77/154
2.83/149
3.16/130
III
IV
V
4.749
5.022
15.867
ꢀ19.4
ꢀ19.4
ꢀ2.5
ꢀ9.7
ꢀ9.1
ꢀ0.8
ꢀ60.4
ꢀ58.4
ꢀ8.2
48.0
45.9
3.8
ꢀ41.5
ꢀ40.9
ꢀ7.7
1ꢀx,1ꢀy,1ꢀz
ꢀx,ꢀy,1ꢀz
x,y,zꢀ1
VI

CrystEngComm
Page 16 of 35
View Article Online
DOI: 10.1039/C7CE01310H
VII
16.276
15.893
ꢀ2.8
ꢀ0.8
ꢀ1.1
ꢀ1.0
ꢀ9.0
ꢀ7.1
5.8
ꢀ7.1
ꢀ1.6
1+x,y,zꢀ1
ꢀx,ꢀy,2ꢀz
C7ꢀH7…Cl14
3.03/119
VIII
7.2
C14ꢀCl14…Cl14
3.554(1)/129
Molecule 5
I
4.887
ꢀ48.0
ꢀ19.8
ꢀ50.0
62.8
ꢀ55.0
x,y,z
N1BꢀH1NB…O1A
C1BꢀH1B…O1A
2.09/170/
2.48/129
2.84/128
2.49/135
3.552(2)
2.10/167/
2.53/129
2.78/128
2.48/137
3.531(1)
3.00/145
2.87/130
C16BꢀH16B…O1A
C8BꢀH8B…O13A
C3A(Cg1)…C16B(Cg6)
N1AꢀH1NA…O1B
C1AꢀH1A…O1B
II
4.891
ꢀ48.7
ꢀ20.3
ꢀ51.0
65.0
ꢀ54.9
ꢀ1+x,y,z
C16AꢀH16A…O1B
C8AꢀH8A…O13B
C16A(Cg3)…C2B(Cg4)
C1BꢀH1B…C15A(Cg3)
C131ꢀH13C…C11B(Cg6)
III
IV
8.184
9.553
ꢀ6.1
ꢀ8.9
ꢀ5.6
ꢀ3.1
ꢀ32.8
ꢀ16.4
22.8
6.9
ꢀ21.6
ꢀ21.5
0.5+x,1.5ꢀy,ꢀz
2ꢀxꢀ0.5+y,0.5ꢀz
C5AꢀH5A…O1B
2.98/165
3.04/166
2.88/137
2.94/141
2.83/171
2.97/131
2.90/153
2.68/122
2.80/117
2.87/141
C4AꢀH4A…C12B(Cg6)
C6AꢀH6A…C11A(Cg3)
C132ꢀH13D…C2B(Cg4)
C14BꢀH14B…C3B(Cg4)
C6BꢀH6B…C2A(Cg1)
C5BꢀH5B…O1A
V
8.270
8.411
ꢀ5.2
ꢀ6.7
ꢀ5.2
ꢀ3.9
ꢀ32.9
ꢀ26.5
23.3
18.5
ꢀ20.1
ꢀ18.5
1ꢀx,ꢀ0.5+y,0.5ꢀz
2ꢀx,ꢀ0.5+y,0.5ꢀz
VI
VII
8.614
ꢀ6.0
ꢀ3.0
ꢀ3.5
ꢀ25.1
ꢀ20.0
16.5
18.2
ꢀ17.5
ꢀ17.0
0.5+x,0.5ꢀy,ꢀz
VIII
12.279
ꢀ11.7
1.5ꢀx,1ꢀy,ꢀ0.5+z
C132ꢀH13F…O13A
C131ꢀH13A…O13B
C3BꢀH3B…C6B(Cg5)
IX
X
9.862
9.612
9.744
12.085
ꢀ5.1
ꢀ3.4
ꢀ3.5
ꢀ4.3
ꢀ2.4
ꢀ3.1
ꢀ2.2
ꢀ2.3
ꢀ18.5
ꢀ16.0
ꢀ17.7
ꢀ23.4
11.4
7.9
ꢀ14.7
ꢀ14.6
ꢀ13.5
ꢀ11.4
0.5+x,0.5ꢀy,ꢀz
ꢀ0.5+x,1.5ꢀy,ꢀz
1ꢀx,0.5+y,0.5ꢀz
1.5ꢀx,1ꢀy,0.5+z
C15AꢀH15A…C12A(Cg3) 2.84/162
XI
XII
9.8
C15ꢀH15B…C9A
2.89/158
3.524(1)
3.543(1)
2.91/129
2.95/136
2.93/137
18.6
C6A(Cg2)…C7B(Cg5)
C7A(Cg2)…C6B(Cg5)
C7AꢀH7A…C14A(Cg3)
C7BꢀH7B…C14B(Cg6)
C131ꢀH13B…C4A(Cg1)
XIII
XIV
XV
13.196
13.196
13.054
ꢀ3.6
ꢀ2.8
ꢀ2.9
ꢀ1.5
ꢀ1.1
ꢀ2.1
ꢀ13.5
ꢀ11.8
ꢀ11.7
8.2
5.9
8.8
ꢀ10.4
ꢀ9.8
0.5ꢀx,1ꢀy,0.5+z
1.5ꢀx,1ꢀy,ꢀ0.5+z
1.5ꢀx,1ꢀy,ꢀ0.5+z
ꢀ7.8

Page 17 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
XVI
13.057
5.516
ꢀ2.0
ꢀ1.9
ꢀ10.5
ꢀ52.3
7.4
ꢀ7.0
2.5ꢀx,1ꢀy,0.5+z
ꢀ1+x,y,z
C132ꢀH13E…C4B(Cg1)
3.02/148
Molecule 6
I
ꢀ34.3
ꢀ11.1
41.8
ꢀ56.0
N1ꢀH1N…O1
2.48/155
2.65/131
C16ꢀH16…O1
Molecular Stacking
C5ꢀH5…O14
II
4.902
4.564
ꢀ26.4
ꢀ18.9
ꢀ12.8
ꢀ10.1
ꢀ65.5
ꢀ63.8
59.1
47.3
ꢀ45.6
ꢀ45.4
1ꢀx,ꢀy,ꢀz
2.90/146
2.72/152
2.92/162
2.93/141
2.84/147
3.07/134
2.71/155
2.99/139
2.84/150
2.70/133
2.47/135/150
3.02/150
C4ꢀH4…C12(Cg3)
C141ꢀH14A…C6(Cg2)
C15ꢀH15…C8(Cg2)
C16ꢀH16…C1(Cg1)
C1ꢀH1…C11(Cg3)
C8ꢀH8…C15(Cg3)
C12ꢀH12…C4(Cg1)
C13ꢀH13…C5(Cg2)
C141ꢀH14B…O14
C5ꢀH5…H14BꢀC14
C6ꢀH6…O14
III
1ꢀx,1ꢀy,ꢀz
IV
V
4.712
4.456
ꢀ18.0
ꢀ12.2
ꢀ12.4
ꢀ7.3
ꢀ61.2
ꢀ55.3
51.5
36.0
ꢀ40.0
ꢀ38.9
2ꢀx,1ꢀy,ꢀz
2ꢀx,ꢀy,ꢀz
VI
16.255
16.101
ꢀ8.0
ꢀ1.5
ꢀ1.8
ꢀ1.5
ꢀ9.3
ꢀ8.4
6.9
5.1
ꢀ12.1
ꢀ6.3
1ꢀx,ꢀy,1ꢀz
x,y,ꢀ1+z
VII
Molecule 7
I
3.388
4.045
8.187
ꢀ19.7
ꢀ16.7
ꢀ12.7
ꢀ8.9
ꢀ6.4
ꢀ5.7
ꢀ95.7
ꢀ86.1
ꢀ24.9
71.3
57.2
17.1
ꢀ52.9
ꢀ51.9
ꢀ26.2
ꢀx,1ꢀy,1ꢀz
1ꢀx,1ꢀy,1ꢀz
x,ꢀ1+y,z
Stacking
II
III
Stacking
C5ꢀH5…O1
2.65/141
2.66/142
2.71/132
2.84/125
3.687(1)
2.82/127
2.42/127/129
2.75/130
2.984/100
C4ꢀH4…O1
C15ꢀH12…O121
C5ꢀH5…O121
C4(Cg1)…C4(Cg1)
C16ꢀH16…O1#
C1ꢀH1…H15ꢀC15
C13ꢀH13…O122
N12ꢀO122…O122
IV
V
7.532
7.422
11.511
ꢀ6.6
ꢀ5.5
ꢀ9.2
ꢀ3.6
ꢀ4.4
ꢀ2.0
ꢀ27.9
ꢀ27.2
ꢀ11.8
14.2
15.0
9.3
ꢀ23.9
ꢀ22.2
ꢀ13.6
ꢀx,2ꢀy,1ꢀz
1ꢀx,ꢀy,1ꢀz
ꢀx,1ꢀy,2ꢀz
VI
VII
14.218
ꢀ1.9
ꢀ0.7
ꢀ9.5
4.5
ꢀ7.7
x,ꢀ1+y,1+z
C6(Cg2)…C13(Cg3)
C7(Cg2)…C14(Cg3)
3.896(1)
3.689(2)
Notes: CentroidꢀCentroid distance corresponds to the distance between the molecular centre of the interacting molecules.
Cg1 :C1ꢀC2ꢀC3ꢀC4ꢀC10ꢀC9/C1AꢀC2AꢀC3AꢀC4AꢀC10AꢀC9A ; Cg2: C5ꢀC6ꢀC7ꢀC8ꢀC9ꢀC10/C5AꢀC6AꢀC7AꢀC8AꢀC9Aꢀ

CrystEngComm
Page 18 of 35
View Article Online
DOI: 10.1039/C7CE01310H
C10A ; Cg3: C11ꢀC12ꢀC13ꢀC14ꢀC15ꢀC16/C11AꢀC12AꢀC13AꢀC14AꢀC15AꢀC16A ; Cg4: C1BꢀC2BꢀC3BꢀC4BꢀC10Bꢀ
C9B ; Cg5: C5BꢀC6BꢀC7BꢀC8BꢀC9BꢀC10B ; Cg6: C11BꢀC12BꢀC13BꢀC14BꢀC15BꢀC16B.
Packing of 1
The molecule 1 crystallizes in triclinic space group
molecular contact resulted from a strong and directional NꢀH···O=C [dN…O: 2.51 Å;
interaction leading to the formation of a molecular chain along the ꢀaxis [motif I, Figure 4(a)].
Pꢀ1 with Z =2 [Figure 4]. The most stabilized
∠NꢀH…O: 165°]
b
Motif I was additionally supported by CꢀH···O [2.80 Å; 125°] and molecular stacking [involving
atoms of the Cg1, Cg2 and Cg3 rings] resulting in a total interaction energy of ꢀ51.7 kJ/mol [Table
4]. The strong NꢀH···O hydrogen bond makes a significant contribution of electrostatic energy
[coulombic + polarization] towards stabilization [~41%]. The dispersion contribution [~59%] was
also significant due to the presence of π···π stacking. As observed in the MESP analysis [Figure
3(a)], the aromatic rings present in the structure of 1 have regions of highly negative electrostatic
potential and, as expected, this resulted in presence of multiple motifs stabilized by multiple CꢀH···π
interactions [Figure 4(a)]. Perpendicular to the bcꢀplain, chains formed by motif I are interlinked by
motifs II and III consisting of Tꢀshaped CꢀH···π interactions (involving atoms of Cg1, Cg2 and Cg3
rings)) [Figure 4(a)]. The H···C(π) distances were always less than 3 Å in these two motifs [Table 4].
The interaction energies for motifs II and III were calculated to be ꢀ39.4 kJ/mol and ꢀ34.9 kJ/mol,
respectively with large contributions to stabilisation from the dispersion energy components [Table
4]. In previous theoretical studies,84 it has been shown that the interaction energy of a single CꢀH···π
interaction can be as high as ꢀ10 kJ/mol in the optimized state. In crystals, the molecular environment
around the CꢀH···π contact becomes important and can contribute towards the dispersion energy
resulting in higher stabilisation. Along the
a
ꢀaxis also, chains formed through motif I were further
V (ꢀ6.3 kJ/mol, an H···H
interconnected by motif IV (ꢀ8.5 kJ/mol, a CꢀH···π interaction),
interaction) and VI (ꢀ6.2 kJ/mol, an H···H interaction) [Figure 4(b)]. These motifs were highly
dispersive in nature with contributions of more than 70% towards stabilization. The weak and highly
dispersive nature of these three motifs suggests that they are largely a consequence of crystal
packing.

Page 19 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
Figure 4: Packing diagram of 1 showing the nature of (a) motifs I, II, III and (b) IV, V and VI.
Packing of 2
Molecule 2 crystallizes in the monoclinic space group P21 with Z=2. The presence of a cyclohexane
ring, in place of the phenyl ring in 1 [Figure 1(b)], results in the presence of additional positive
electrostatic regions [Region B, Figure 3(b)]. The molecular packing in 2 is therefore significantly
different to that found in 1 [Figure 5(a)ꢀ(b)]. Motif I forms a molecular chain along the aꢀaxis
through a short and directional NꢀH···O=C hydrogen bond [dN…O: 2.16 Å; ∠NꢀH…O: 160°] with
additional stability provided by CꢀH···O [dH…O: 2.77 Å; ∠CꢀH…O: 128°] interaction and molecular
stacking [involving Cg1, Cg2 and Cg3]. The interaction energy of motif I was calculated to ꢀ52.4
kJ/mol [Table 4] with comparable contributions from the electrostatic [51%] and dispersion energy
[49%] components towards the stabilization [Table 4]. Motif II consisted of a CꢀH···π(Cg1)
interaction which is augmented by π···π interactions [involving Cg1, Cg2 and Cg3]. This motif was
again highly dispersive with an approximately 76% contribution towards stabilization. Another

CrystEngComm
Page 20 of 35
View Article Online
DOI: 10.1039/C7CE01310H
highly dispersive CꢀH···π(Cg2) contact [motif IV, ꢀ12.3 kJ/mol] stabilizes the packing along the bꢀ
axis. The cyclohexane ring was expected to be actively involved in the formation of highly
dispersive H···H contacts [Figure 5(a) and (b)]. Motif III [ꢀ16.7 kJ/mol], V[ꢀ19.0 kJ/mol], VI [ꢀ8.6
kJ/mol], and VII [ꢀ7.4 kJ/mol], all involved H···H interactions although not exclusively emanating
from the cyclohexane ring. The overall contribution of dispersion towards stabilization was in excess
of ~75% from these motifs . The H···H distance in these contacts ranged from 2.44 – 2.68 Å.
Figure 5: Packing diagram of 2 showing the nature of (a) motifs I, IV, V, VI and VII (b) II and III.
Packing of 3
Molecule 3 crystallizes in monoclinic space group P21/c with Z=4. Unlike other molecules, motif I
resulting from the NꢀH···O=C hydrogen bond [dH…O: 1.93 Å; ∠NꢀH…O: 167°] forms a zigꢀzag
arrangement with molecules linked along c rather than a molecular chain [Fig. 6(a)]. This was also
the shortest NꢀH···O interaction observed among the molecules reported in this study [Table 4]. As
with the other molecules, motif I was additionally supported by a number of CꢀH···O and CꢀH···π
interactions with an interaction energy of ꢀ61.7 kJ/mol. This was distributed between electrostatic,

Page 21 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
~55% and dispersive ~45% contributions to the stabilization. Motif II [ꢀ29.0 kJ/mol] consisted of
offset π···π interactions [involving atoms of the Cg1, Cg2 and Cg3 rings] which were highly
dispersive in nature with ~80% contribution towards stabilization. Motif III [ꢀ17.8 kJ/mol] and IV [ꢀ
10.3 kJ/mol], and which were due exclusively to CꢀH···π hydrogen bonds (involving the Cg2 and
Cg3 rings) [Figure 6(b)ꢀ(c)] further stabilised the packing. The H···C (π) distances in these
interactions were in the range 2.93ꢀ2.95 Å with CꢀH···C(π) angles in the range being 142° and 154°
[Table 4]. Further stability perpendicular to the ac-plane [Figure 6(c)] was provided by the presence
of two different but highly dispersive [>75%] H···H interactions [motif V, ꢀ8.9 kJ/mol; motif VI, ꢀ
8.2 kJ/mol].
Figure 6: Packing diagram of 3 showing the nature of (a) motifs I (b) II, III and IV (c) V and VI.
Packing of 4
Molecule 4 crystallizes in triclinic space group Pꢀ1 with Z=2. The molecular packing [Figure 7(a)ꢀ
(b)] was very similar to that for 1 with molecular chains formed by NꢀH···O=C hydrogen bonds and
interconnected further [Figure 7(b)] by various motifs including several CꢀH···π contacts (involving
atoms of the Cg1, Cg2 and Cg3 rings) [motifs II – V, Figure 7(b)]. The energy of each of these
motifs was > 40 kJ/mol with dispersion being the dominant contributor towards stabilization [Table
4]. However, the unique feature of the molecular packing of 4 was the participation of the Cl atom in
forming both hydrogen [Figure 7(c)] and halogen bonds [Figure 7(b)]. Motifs VI [ꢀ7.7 kJ/mol] and
VII [ꢀ7.1 kJ/mol] result from two discrete C6ꢀH6···Cl14 and C7ꢀH7···Cl14 hydrogen bonds that

CrystEngComm
Page 22 of 35
View Article Online
DOI: 10.1039/C7CE01310H
combine with the NꢀH···O contact, motif 1,to generate sheets of molecules in the ac plane, Fig 7(c).
The Cl···Cl halogen bonds, motif VIII, form dimers that are linked into double chains along a by the
NꢀH···O hydrogen bonds, Fig 7(a). These CꢀH···Cl hydrogen bonds were highly dispersive in nature
with contributions towards stabilization of ~70% in both motifs, VI and VII. The Cl···Cl halogen
bond was also a dispersive Type I interaction85 [dCl…Cl: 3.554(1) Å; ∠CꢀCl…Cl: 129°]. However this
contact is weak; despite the Cl···Cl distance being less than the sum of vdW radii of the two Cl
atoms.86 the interaction energy was observed to be only ꢀ1.9 kJ/mol.
Figure 7: Packing diagram of 4 showing the nature of (a) motifs VIII (b) I, II, III, IV and V (c) VI
and VII.
Packing of 5
The two unique molecules of 5 crystallize in the orthorhombic space group P212121 with Z=8. The
presence of two molecules in the asymmetric unit resulted in extremely complicated molecular
packing interactions [Figure 8(a)ꢀ(c)]. In the ac-plane, the packing is stabilized by formation of
chains generated by motif I [ꢀ55.0 kJ/mol] and motif II [ꢀ54.9 kJ/mol] contacts. These resulted from
alternating NꢀH···O interactions between the two unique molecules in the asymmetric unit. These
contacts were stabilised further by various CꢀH···O and π···π stacking interactions [Table 4]. In
three dimensions packing was extensively supported by the presence of eleven different motifs each

Page 23 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
exclusively consisting of CꢀH···π contacts (involving atoms of the Cg1ꢀCg6 rings in different
motifs). The interaction energies in these eleven motifs range from ꢀ21.6 kJ/mol to ꢀ7.0 kJ/mol with
dispersion contributing more than 60% towards the stabilization of the molecular pairs [Table 4].
Motifs IV [ꢀ21.5 kJ/mol] and VII [ꢀ17.5 kJ/mol] also included CꢀH···π hydrogen bonds (Cg1 and
Cg6 rings) but these were additionally supported by CꢀH···O hydrogen bonds involving the oxygen
atom of the carbonyl group. The oxygen atoms of the methoxy groups in both molecules are
involved in similar C131ꢀH13A···O13B and C132ꢀH13F···O13A hydrogen bonds [motif VIII, ꢀ17.0
kJ/mol]. Stabilisation of this motif has substantial contribution from the electrostatic component.
Motif XII [ꢀ11.4 kJ/mol] consisted of a π···π stacking interaction involving the atoms of the Cg1 ring
with C···C distance being ~3.5Å.

CrystEngComm
Page 24 of 35
View Article Online
DOI: 10.1039/C7CE01310H
Figure 8: Packing diagram of 5 showing the nature of (a) motifs I, II, VIII, XI, XIII, XIV, XV and
XVI (b) III, IV, V and X (c) VI, VII, IX and XII.

Page 25 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
Packing of 6
Molecule 6 crystallizes in the triclinic space group Pꢀ1 with Z =2. The packing of 6 is largely similar
to those observed for 1 and 4 again involving chains formed by the NꢀH···O=C hydrogen bonds
[motif I, ꢀ56.0 kJ/mol] interconnected by several highly stabilized and dispersive motifs [II (ꢀ45.6
kJ/mol), III (ꢀ45.4 kJ/mol), IV( ꢀ40.0 kJ/mol) and V(ꢀ38.9 kJ/mol) consisting of different CꢀH···π
interactions [Figure 9(a)ꢀ(b)]. In motif II the CꢀH···π contact (Cg3 ring) is augmented by a CꢀH···O
hydrogen bond [dH…O: 2.90 Å; ∠CꢀH…O: 146°]. In the bcꢀplane, additional CꢀH···O hydrogen bonds,
motif VI [ꢀ12.1 kJ/mol] and VII [ꢀ6.3 kJ/mol] gave additional stability to the molecular packing
[Figure 9(b). Motif VI has a significant stabilising contribution from both electrostatic and dispersive
energy components [Table 4], while motif VII was highly dispersive (> 75%) due to the relatively
large intermolecular H···O distance [3.02 Å, Table 4].

CrystEngComm
Page 26 of 35
View Article Online
DOI: 10.1039/C7CE01310H
Figure 9: Packing diagram of 6 showing the nature of (a) motifs I, II, III and V and (b) IV, VI and
VII.
Packing of 7
Molecule 7 crystallizes in the triclinic space group Pꢀ1 with Z=2. The unique feature of the crystal
structure of this molecule is the absence of the strong NꢀH···O=C interaction seen in the other

Page 27 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
compounds reported here. This is because of the o-substituted phenyl ring where the formation of
intramolecular NꢀH···O interaction [Figure 1(g)] involving the –NO2 substituent precludes the
formation of the intermolecular NꢀH···O hydrogen bond. Also, it was observed in the MESP map of
this molecule, that the phenyl ring was clearly electron deficient [Figure 3(h), region B] resulting in
a high propensity for π···π stacking interactions rather than the CꢀH···π interactions that were
prevalent in the related molecules 1ꢀ6 [Table 4]. Along the aꢀaxis, the packing is stabilized by two
extensive molecular stacking interactions [Figure 10(a)]. The interaction energies of these two
motifs were ꢀ52.9 kJ/mol (motif I) and ꢀ51.9 kJ/mol (motif II), respectively with dispersion being the
highly dominant contribution towards stabilization being more than 75% of the total in both cases.
Another weak and dispersive π(C6) ···π(C13) interaction occurs along the aꢀaxis with an interaction
energy of only ꢀ7.7 kJ/mol [motif III, Figure 10(a)]. The presence of three oxygen atoms in the
molecule results in the formation of multiple CꢀH···O interactions which further stabilized the
packing in both the ac and bc planes [Table 4]. Motif III [ꢀ26.2 kJ/mol] consisted of three different
CꢀH···O interactions where the H···O distance were less than the sum of vdW radii of H and O and
the interaction energies have significant contributions from both the electrostatic and dispersion
energy components towards stabilization [Table 4]. Motifs IV [ꢀ23.9 kJ/mol] and V [ꢀ22.2 kJ/mol]
also result from CꢀH···O interactions with further stability provided by the presence of additional
π···π and H···H interactions, respectively [Table 4]. These motifs make significant contributions to
the dispersion energy of the system. The –NO2 group is also involved in the formation of an
inversion dimer through C13ꢀH13···O122 hydrogen bonds. These contacts enclose an R2 (10) ring
2
and have an interaction energy of ꢀ13.6 kJ/mol. Another unique feature of this motif is that the
centrosymmetric interaction necessitates an additional close O···O contact [dO…O: 2.984(3) Å; ∠Nꢀ
O…O: 100°] as a result of which, this motif has a significant contribution from dispersion [~51%]
towards its stabilization [Figure 10(b)].

CrystEngComm
Page 28 of 35
View Article Online
DOI: 10.1039/C7CE01310H
Figure 10: Packing diagram of 7 showing the nature of (a) motifs I, II, III, IV and V and (b) VI and
VII.
Analysis of Isostructural features
It was clearly evident from the analysis of crystal packing that there are significant similarities
between the molecular arrangements in molecules 1 [Figure 4], 4 [Figure 7] and 6 [Figure 9].
Therefore, it was interesting to quantitatively investigate whether any 1Dꢀ, 2Dꢀ or 3ꢀD similarities
existed between these structures. A comparison of 1 and 4 revealed the presence of a 1D

Page 29 of 35
CrystEngComm
View Article Online
DOI: 10.1039/C7CE01310H
supramolecular construct (SC) with x = 7.8 and D = 0.12 Å [Figure S8]. This 1D similarity is
principally due to the formation of molecular chains through the NꢀH···O interactions found in both
molecules. A similar 1ꢀdimensionalꢀsupramolecular construct, 1DꢀSC, is also found between 1 and 6
with x and D being 8.4 and 0.04 Å [Figure S9]. Comparison of 4 and 6 reveals the presence of a 3Dꢀ
SC with x = 0.21 and D =5.5 Å [Figure S10]. This similarity was largely due to the fact that 4 and 6
both crystallize in the same space group with reasonably similar cell parameters [Table 1]. No degree
of supramolecular construct was observed for any other pairs of molecules in the series.
2Dimensional Fingerprint Plots
The results from the 2D Fingerprint plots [Figure 11] for 1ꢀ7 reveal that the contributions of H···C
interactions to the structural stability ranged from 10.8% (in 7) to 46% (in 1) while that from H···H
contacts ranged from 26.6% (in 4) to 63.7% (in 2). The H···C contacts were the major contributors to
the packing in the case of 1, 4 and 6 owing to the presence of extensive networks of CꢀH···π
interactions. Molecule 2 had an H···C contribution of 24.3% but this was overshadowed by the
H···H contribution (63.7%) due to the presence of a cyclohexane ring in place of the phenyl rings
found in the other molecules. The contribution of H···H (46.2%) was slightly higher than H···C
(42.4%) in 3 due to the–CH3 substituent on the phenyl ring. Molecule 5 with two molecules in the
asymmetric unit had an abundance of H···H interactions (45%) compared to H···C contacts (38.7%).
As discussed earlier, the absence of a strong NꢀH···O hydrogen bond resulted in the packing of 7
being stabilized by π···π stacking interactions rather than CꢀH···π hydrogen bonds. This resulted in
the contribution of C···C (16.8%) being higher than H···C (10.8%) interactions. It is also interesting
to note that the contribution of C···C was observed to be significant only in the case of 7. Also, the
high contribution of H···H (38.0%) contacts in 7 in comparison to H···C interactions can be
attributed to the absence of CꢀH···π interactions rather than a much higher propensity for H···H
contacts. Indeed when compared to other molecules, the contribution of H···H in 7 was second
lowest behind those observed in molecule 4. The low magnitude of H···H (26.4%) in 4 was due to
the presence of a Cl substituent in the molecule resulting in significant CꢀH···Cl hydrogen bond
formation with a contribution of 15.1% from these H···Cl interactions [Table S1]. The contribution
of O···H hydrogen bonds ranged from 8.0% (in 1) to 27.1% (in 7). Inevitably, the strong NꢀH···O
hydrogen bonds were the major source of these O···H contributions in molecule 1ꢀ6. For 7, the large
27.1% contribution results from the presence of the ꢀNO2 substituent whose oxygen atoms actively
participate in forming multiple CꢀH···O hydrogen bonds. The combined contribution of all the