Structural elucidation and study of intermolecular interactions in meso-tetratolylporphyrins

Article abstract of DOI:10.1142/S1088424616501017

Synthesis and crystal structure analysis of meso-tetratolylporphyrins, 1-5 combined with computational Hirshfeld surface analysis were investigated. The crystal packing of porphyrins 1, 3 and 4 are arranged in an "orthogonal fashion" whereas 2 and 5 are i

Full text of DOI:10.1142/S1088424616501017

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2016; 20: 1–10
DOI: 10.1142/S1088424616501017
Published at http://www.worldscinet.com/jpp/
Structural elucidation and study of intermolecular
interactions in meso-tetratolylporphyrins
Rahul Soman, Subramaniam Sujatha and Chellaiah Arunkumar*
Bioinorganic Materials Research Laboratory, Department of Chemistry, National Institute of Technology Calicut,
Kozhikode, Kerala 673 601, India
Received 8 April 2016
Accepted 3 June 2016
ABSTRACT: Synthesis and crystal structure analysis of meso-tetratolylporphyrins, 1–5 combined with
computational Hirshfeld surface analysis were investigated. The crystal packing of porphyrins 1, 3 and 4
are arranged in an “orthogonal fashion” whereas 2 and 5 are in a “slip-stack or off-set fashion” through
various intermolecular interactions. Compound 2 exhibits saddle geometry whereas 5 showed a domed
geometry as evident from the single crystal X-ray diffraction studies. The enhancement of non-planarity
in 2 is probably due to the presence of numerous intermolecular interactions caused by the presence
of trifluoroacetate anions on both faces of the porphyrin in addition to the bulky bromine groups at the
b-pyrrole positions. In 5, the non-planarity is merely due to the metal coordination at the porphyrin core
as pentacoordinated MnIII center with a chloro ligand in the axial position. Hirshfeld surface analysis was
performed in order to analyze the various intermolecular interactions present in these porphyrins and the
result was discussed.
KEYWORDS: tolylporphyrins, non-planar porphyrins, crystal structure analysis, Hirshfeld surface
analysis, intermolecular interactions.
P-450 [4]. It is well-known that the b-halogenated
non-planar porphyrin macrocycle shows remarkable
bathochromic shift with smaller extinction coefficient
compared planar analogs [4]. Theoretical studies
reveal that the major cause for the red shift is due to
nonplanarity-induced destabilization of the porphyrin
HOMOs [5]. Insertion of small metal ion at the porphyrin
core results in substantial changes in the degree of
non-planarity, conformational flexibility and electron
density distribution. It is also possible to induce the
non-planarity in planar porphyrins by core modification,
ring reduction/oxidation and by crystal packing effects.
Among the various types of non-planar conformations of
the porphyrin macrocycle, the most common distortions
are the ruffling (B1u) and saddling (B2u) conformations
in addition to the doming (A2u), waving (Eg) and
propellering (A1u) structures [6]. The dome structure is
usually seen in metalloporphyrins possessing an axial
fifth ligand. There has been a growing interest in the study
of synthetic non-planar porphyrins to better understand
the biological role of non-planar heme prosthetic groups
INTRODUCTION
Porphyrins are tetra-pyrrolic, highly colored
pigments and nature has chosen them for the biological
functions such as electron transfer, oxygen transport,
photosynthesis energy transduction, etc., because of
their highly flexible skeleton which allows a range
of distorted non-planar conformations [1, 2]. The
distorted conformations are ubiquitous in the hemes of
hemoproteins, the pigments of photosynthetic proteins
and cofactor F430 of methylreductase. The introduction
of substituents at the b-pyrrole position leads to
distortion of the porphyrin core from planarity due to
steric repulsion and these non-planar conformations are
employed as models for naturally available tetrapyrrolic
pigments [3]. In particular, distorted porphyrins with
sterically hindered electron withdrawing substituents are
employed to mimic the catalytic activity of cytochrome
*Correspondenceto:ChellaiahArunkumar,email:arunkumarc@
nitc.ac.in, tel: +91 495-228-5307, fax: +91 495-228-7250
Copyright © 2016 World Scientific Publishing Company

2
R. SOMAN ET AL.
H3C
CH3
Structural characterization by single crystal X-ray
diffraction studies
Synthesis of tolylporphyrins, H2TTP, 1; [H4TTPBr42+
(CF3COO-)2 (C2H4Cl2)], 2; ZnIITTP, 3; MnIITTP (H2O)2,
4 and MnIIITTPCl, 5 is reported and are structurally
characterized by single crystal X-ray diffraction
analysis. Compounds, 1–4 are crystallized in monoclinic
system with space groups, P21/c, P21/n, C2/c and P21/n
respectively, whereas 5 in triclinic with P-1 (Table 1).
The ORTEP and molecular crystal packing diagrams for
compounds, 1–5 are shown in Figs 3–7.
N
M
N
X
X
X
X
N
N
CH3
H3C
X = H; M = 2H, 1
X = Br; M = 2H, 2
X = H; M = Zn(II), 3
The ORTEP diagrams of compound 1 show a planar
arrangement of the porphyrin core (Figs 3a and 3b) and
the molecular crystal packing is through the formation of
“orthogonal arrangement” of molecules or p–p stacking
lead to form a one dimensional array (Fig. 4b) involving
(ph)C–H∙∙∙C(ph) and (methyl)C–H∙∙∙N(pyr) interactions (Table 2).
The diprotonated form of antipodal tetrabrominated
compound, 2 [H4TTPBr42+ (CF3COO-)2 (C2H4Cl2)] is found
to be non-planar, exhibits saddle geometry (Figs 3c and
3d) and the average mean plane deviation of the b-pyrrole
and meso-carbon atoms are found to be 1.1378(2) Å and
0.0410(2) Å respectively, which is much greater than that
of the reported tetrabrominated freebase 4-butoxyphenyl
porphyrin, [12] ( 0.50(3) Å and 0.038(3) Å). The
enhanced non-planarity observed in 2 indicates that there
is an effective interaction between the CF3COO- counter
anions and porphyrin core due to their close proximity
involving various intermolecular interactions. Moreover,
the presence of two CF3COO- anions on both faces of the
porphyrin core leads to diacid formation that enhances the
non-planar nature of the porphyrin in addition to the bulky
substituent present at the b-pyrrole positions.
X = H; M = Mn(II)(H2O)2, 4
X = H; M = Mn(III)Cl, 5
Fig. 1. Molecular structure of meso-tetratolylporphyrins under
study
present in biomolecules. The first example of a sterically
ruffled porphyrin bearing meso-substituents was
reported by Senge et al. [7]. The non-planar porphyrins
generally exhibit more intermolecular interactions
compared to their planar analogs which control their
structure and in turn the functional properties. Recently,
we reported the intermolecular interactions of planar
and non-planar fluorinated porphyrins bearing different
meso-substituents [8]. Here, we report the synthesis and
the detailed crystal structure analysis of few planar and
non-planar meso-tetratolylporphyrins (Fig. 1) and their
structural features are compared.
RESULTS AND DISCUSSION
Furthermore, the molecular crystal packing of 2 forms
a “slip-stack or off-set arrangement” of molecules which
is presumably due to the non-planarity of the core and
hence there is no effective p–p stacking observed which
is depicted in Fig. 4c involving several intermolecular
interactions, viz., N–H∙∙∙O, N–H∙∙∙C, C–H∙∙∙O, C–H∙∙∙p,
C–H∙∙∙N, Br∙∙∙O, Br∙∙∙Br, etc. (Table 2). Moreover, the
intermolecular interactions in 2 were found to be mainly
of hydrogen bonding between the oxygen atom of the
CF3COO- anions and imino hydrogen of the porphyrin
core and they are very strong owing to their close
proximity; they found on both faces of the porphyrin core
and in the range of 2.501–2.684 Å (Fig. 4a).
In 3, the zinc(II) centre is tetra coordinated with
the porphyrin core nitrogens, forms a square planar
arrangement and the porphyrin core is found to be planar
withoutanydistortions(Figs5aand5b).Thecrystalpacking
diagram of 3 is in a “zigzag arrangement” of molecules
formed through mainly of (ph)C–H∙∙∙C(ph) and (ph)C∙∙∙C(ph)
interactions (Fig. 5c). The average Zn–N and Zn–Cmeso
distances in 3 are 2.030(2) Å and 3.442(2) Å respectively
which are comparable with the reported zinc(II)-meso-
tetra(4-tolyl)porphyrins [13] (2.037(5), 2.036(18) Å and
Optical properties
5,10,15,20-Tetratolylporphyrin, H2TTP ligand, 1, 2,3,-
12,13-terabromo-5,10,15,20-tetratolylporphyrin, H2TTPBr4
ligand, 2 were synthesized using the method reported by
Lindsey et al. [9] and Bhyrappa et al. [10] respectively
and the metal complexes, 3–5 were prepared by the
literature method [11] to afford the desired complexes
(Scheme 1).
The UV-visible spectra of porphyrins, 1 and 2 are very
well matched with the reported H2TPP and H2TPPBr4 [10]
exhibiting the characteristic Soret and Q-bands. Notably,
upon bromination of 1 to form 2, it is noted that there
is a reduction in the number of Q-bands from 4 to 3 as
observed in H2TPPBr4. The overlayed spectra for H2TPP
and H2TPPBr4 and 1 and 2 was made and portrayed in
Figs 2a and 2b respectively.
As seen from Fig. 2b, the Soret band of the antipodal
brominated product of H2TTP shows red shifted
absorption spectrum of 19 nm, similar to brominated
H2TPP (Fig. 2a) which confirms the formation of
tetrabrominated product of 2.
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 2–10

STRUCTURAL ELUCIDATION AND STUDY OF INTERMOLECULAR INTERACTIONS IN meso-TETRATOLYLPORPHYRINS
3
H3C
CH3
H3C
CH3
CHO
N
N
Br
H
H
Br
Br
Propionic acid /
Propionic anhydride
NBS, CHCl3
Reflux, 6 hrs
N
N
N
N
+
Reflux, 2 hrs
Br
N
H
H
H
N
N
CH3
1
2
35 %
CH3
CH3
H3C
H3C
80 %
MnIICl2, DMF
air, 5 hrs
ZnIIacetate,
CHCl3 / MeOH
MnIICl2, DMF
N2, 5 hrs
H3C
CH3
H3C
CH3
H3C
CH3
N
N
N
Cl
N
N
Zn
N
N
N
N
Mn
Mn
N
N
N
3
4
5
CH3
H3C
96 %
CH3
CH3
H3C
H3C
80 %
75 %
Scheme 1. Synthesis of meso-tetratolyl porphyrins
Fig. 2. Overlayed UV-visible spectra of porphyrins, (a) H2TPP and H2TPPBr4; (b) H2TTP, 1 and H2TTPBr4, 2 in CH2Cl2 (6.66 ×
10-6 M) at 298 K
3.444, 3.449 Å) as well as the four coordinate ZnTPP
[14] (2.037(2) Å and 3.447 Å); whereas the average Zn–N
distance is less than that of five- and six-coordinate ZnII
complexes (2.052(4) and 2.057(4) Å) [15].
Another set of planar and non-planar porphyrins
in the present study is 4 (hexacoordinated MnII) and 5
(pentacoordinated MnIII), which are differing each other
by simple metal coordination at the porphyrin core.
In 4, the water molecules are present in the apex
positions which make the MnII ion to fit well into the
porphyrin core and the core is found to be planar in
nature (Figs 6a and 6b). Like 1, the crystal packing of
4 also exhibits “orthogonal arrangement” of molecules
through (ph)C–H∙∙∙C(ph) interaction forming well-stabilized
one dimensional array (Fig. 7a).
Due to the presence of an axial ligand (chloro) in 5,
the porphyrin core is domed in nature and it is slightly
deviated from its planarity, the average mean plane
displacement is 0.2963(3) Å (Fig. 6d). The crystal
packing in 5 is seen as “slip-stack or off-set fashion” as
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 3–10

4
R. SOMAN ET AL.
Table 1. Crystal structure data of porphyrins under study, 1, H2TTP; 2, H4TTPBr42+ (CF3COO-)2 (C2H4Cl2); 3, ZnIITTP; 4, MnIITTP
(H2O)2; 5, MnIIITTPCl
H2TTP, 1
H2TTPBr4 (CF3COO-)2
ZnIITTP, 3
MnIITTP (H2O)2, 4
MnIIITTPCl, 5
(C2H4Cl2), 2
Formula
CCDC
C48H38N4
1041763
Monoclinic
P21/c
C54H40Br4Cl2F6N4O4
956522
Monoclinic
P21/n
C48H36N4Zn
1058016
Monoclinic
C2/c
C48H40MnN4O2
1041764
C49H38Cl2MnN4
980778
Crystal system
Space group
Colour
Monoclinic
P2/n
Triclinic
P-1
Purple
Dark green
15.4215 (7)
15.1724 (7)
25.5568 (12)
90
Pink
Dark green
Dark green
11.1373 (5)
13.1844 (8)
28.0681 (16)
82.437 (2)
86.787 (2)
81.002 (2)
4032.7 (4)
4
a, Å
9.9183 (9)
9.1489 (9)
21.407 (2)
90
32.2573 (19) 14.0459 (13)
b, Å
9.5520 (6)
14.9758 (8)
90
9.9081 (10)
18.9491 (16)
90
c, Å
a, (deg)
b, (deg)
g, (deg)
107.136 (6)
90
94.377 (2)
90
112.373 (5)
90
96.228 (4)
90
Volume, Å3
1856.2 (3)
2
5962.4 (2)
4
4267.0 (4)
4
2621.5 (4)
2
Z
Dcalcd, mg/m3
l, Å
1.200
1.463
1.143
0.963
1.332
0.71073
296 (2)
3248
0.71073
296 (2)
0.71073
296 (2)
3753
0.71073
296 (2)
4603
0.71073
296 (2)
T, K
No. of unique reflections
10285
14096
No. of parameters refined 241
712
244
253
1046
GOF on F2
1.015
1.031
1.033
1.030
1.002
a
R1
0.0630
0.1717
0.0629
0.0415
0.1156
0.0738
0.2176
0.0529
wR2b
0.1754
0.1326
a R1 = S||Fo|–|Fc||/S|Fo|; Io > 2s (Io). b wR2 = [S w(Fo2 –Fc2)2/Sw(Fo2)2]1/2.
observed in the case of non-planar porphyrin 2 molecule
that indicates the less effective interactions between the
porphyrin molecules.
medium intense red spots for O∙∙∙H close contact and big
intense red spot for O∙∙Br close contacts (Figs 8a–8e).
Similarly, in the HS of planar manganese porphyrin 4,
only the C∙∙∙H close contact is seen as small red spot
whereas its non-planar analog 5 shows several medium
intense red spots for H∙∙∙H close contacts and faint red
spots for C∙∙∙H close contacts. Also, the planar zinc(II)
porphyrin 3 shows only the C∙∙∙H close contacts as small
red spots. These results indicate that the non-planar
porphyrins 2 and 5 exhibit several strong intermolecular
interactions compared to the planar analogs.
Overall, the planar porphyrins, 1, 3 and 4 possess
similar kind of intermolecular interactions and they are
stabilized mainly of the type of (ph)C–H∙∙∙C(ph) contacts
which is in the range of 2.81 Å and the packing of
molecules are in the “orthogonal fashion”; whereas in the
case of non-planar porphyrins of 2 and 5, the molecules
are arranged in a “slip-stack or off-set fashion” through
various intermolecular interactions.
The 2D fingerprint plots (FPs) of 1–5 indicating
different inter-atomic interactions present in these
crystals are shown in Figs 8f–8j. In planar porphyrins, the
major contribution comes from the C∙∙∙H [28% in 1; 26%
in 3; 12% in 4], and H∙∙∙H [64% in 1; 48% in 3; 52% in
4] contacts whereas in the case of non-planar porphyrins,
apart from the major interactions detailed above, the
interactions involving halogens of the solvent molecule
are also observed (Fig. 9). In 2, H∙∙∙F/Cl/Br interaction
accounts 24% and in 5 the H∙∙∙Cl contact accounts 15%.
The distribution of individual intermolecular interactions
Study of intermolecular interactions
To analyze and quantify the various non-covalent
interactions present in the crystal packing of planar and
non-planar porphyrins (1–5), Hirshfeld surface (HS)
analysis have been carried out using Crystal Explorer 3.1
[16]. The HSs mapped with dnorm for the planar porphyrin
1 show the (methyl)C–H∙∙∙N(pyr) close contact with small red
spots whereas its non-planar counterpart shows several
red spots such as fainted one for C∙∙∙H close contact,
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 4–10

STRUCTURAL ELUCIDATION AND STUDY OF INTERMOLECULAR INTERACTIONS IN meso-TETRATOLYLPORPHYRINS
Table 2. Distances (in Å) for the different types of interactions in the crystal packing of porphyrins, 1–5
5
Interactionsa
1b
2b
3b
4b
5b
(ph)C–H∙∙∙C(ph)
2.881 (4)
—
—
2.750 (4)
—
2.808 (4)
—
—
(ph)C–H∙∙∙C(b-pyr)
(ph)C–H∙∙∙C(methyl)
(methyl)C–H∙∙∙C(b-pyr)
(methyl)C–H∙∙∙C(ph)
(methyl)C–H∙∙∙C(methyl)
(ph)C–H∙∙∙C(ph)
—
2.837–2.874 (4)
—
—
—
—
2.855 (2)
—
—
—
—
2.875 (2)
—
—
—
—
—
2.850–2.861 (4)
—
—
—
2.795–2.827 (4)
—
—
—
—
2.803–2.855 (4)
(b-pyr)C–H∙∙∙C(ph)
(methyl)C–H∙∙∙N(pyr)
(ph)C∙∙∙C(ph)
—
2.781–2.820 (6)
—
—
—
—
2.704 (4)
—
—
—
—
—
3.334 (2)
—
—
—
(methyl)C∙∙∙C(methyl)
(b-pyr)C∙∙∙M(Mn)
—
—
—
3.395 (2)
—
—
—
—
3.644 (2)
-
(ph)C–H∙∙∙O(CF3COO )
—
2.565–2.684 (4)
2.501 (1)
1.776–1.870 (4)
2.760–2.785 (4)
2.533 (2)
2.627 (2)
3.068 (2)
—
—
—
—
-
(methyl)C–H∙∙∙O(CF3COO )
—
—
—
—
-
(b-pyr)N–H∙∙∙O(CF3COO )
—
—
—
—
-
(b-pyr)N–H∙∙∙C(CF3COO )
—
—
—
—
(ph)C–H∙∙∙F(ph)
(methyl)C–H∙∙∙F(ph)
(ph)C∙∙∙F(ph)
—
—
—
—
—
—
—
—
—
—
—
—
(b-pyr)H∙∙∙H(b-pyr)
(ph)H∙∙∙H(ph)
—
—
—
2.203 (2)
—
2.368 (2)
—
—
—
2.165–2.199 (3)
(methyl)H∙∙∙H(ph)
—
—
—
2.181–2.248 (4)
-
(b-pyr)C–Br∙∙∙O(CF3COO )
—
3.090–3.110 (4)
3.090 (2)
2.657–2.914 (6)
—
—
—
—
—
Br∙∙∙Br
—
—
—
-
(b-pyr)N∙∙∙O(CF3COO )
—
—
—
a Different types. b Value in parenthesis gives the number of interactions of each types per molecule
on the basis of HS analysis for all the compounds is
shown in Fig. 9.
(Note: we used propionic anhydride in place of
propionic acid while refluxing it by which the
excess moisture content present in the acid can be
removed). The antipodal b-pyrrole bromination of
1 was done using the modified literature method
[10]. Chloroform solution of 1 was stirred and
refluxed with 6 equivalents of freshly recrystallized
N-bromosuccinimide (NBS) and the reaction was
monitored with TLC and UV-visible spectroscopy.
After 2 h of time, excess 4 equivalents of NBS
was added and no lower brominated products were
found. The tetrabrominated product, 2 is confirmed
by UV-visible spectroscopic analysis comparing
it with the antipodal brominated product of meso-
tetraphenylporphyrin (H2TPPBr4). The resulting
product (2) was dried and washed twice with
methanol and purified by column chromatography
followed by recrystallization in chloroform/methanol
solution. The recrystallized product 2 was found
EXPERIMENTAL
Materials and methods
All the chemicals employed here for the synthesis
were commercially available reagents of analytical grade
and were used without further purification. Solvents
used for the synthesis were purified using the available
literature methods [17].
Synthesis of 5,10,15,20-tetratolylporphyrin, its
metal complexes and 2,3,12,13-tetrabromo-
5,10,15,20-tetratolylporphyrin
5,10,15,20-tetratolylporphyrin, H2TTP ligand,
1, was prepared using Adler–Longo method.
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 5–10

6
R. SOMAN ET AL.
Fig. 3. ORTEP diagrams, (a, c) top and (b, d) side-on view of 1 and 2 (solvent molecules and disordered components removed for
clarity and shown in 40% probability ellipsoids); and (e) average mean plane displacement of all atoms in 2 molecule
Fig. 4. (a) Wireframe structure of 2 with CF3COO- anions and a dichloroethane molecule indicating various intermolecular
interactions, color scheme: grey-carbon, blue-nitrogen, red-oxygen, green-fluorine, brown-bromine, yellow-chlorine; (b) orthogonal
arrangement of 1 viewed along ‘bc’ plane lead to form a one dimensional array; (c) slip-stack or off-set arrangement of 2 viewed
down ‘a’ axis through various intermolecular interactions
to be poorly soluble in chlorinated solvents, and
hence trifluoroacetic acid is used for crystallization
which yields the diprotonated product, H4TTPBr42+
(CF3COO-)2 (C2H4Cl2) (Note: NBS was purified as
per the literature method). The metal complexes of 3–5
were prepared by the literature method [11] to afford
the desired complexes, yielded in 75–96% (Scheme 1).
Manganese metalation was performed by treating 2 with
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 6–10

STRUCTURAL ELUCIDATION AND STUDY OF INTERMOLECULAR INTERACTIONS IN meso-TETRATOLYLPORPHYRINS
7
Fig. 5. ORTEP diagrams (a) top and (b) side-on view of 3; (c) zigzag arrangement of 3 formed through (ph)C–H∙∙∙C(ph) and (ph)C∙∙∙C(ph)
interactions viewed down along ‘ab’ plane
Fig. 6. ORTEP diagrams, (a, c) top and (b, d) side-on view of 4 and 5 (solvent molecules and disordered components removed for
clarity and shown in 40% probability ellipsoids)
MnIICl2 in N,N-dimethylformamide in presence and
absence of nitrogen atmosphere, resulted the formation
of MnIITTP and MnIIITTPCl respectively.
using appropriate solvent systems. All the crystals were
grown at room temperature and single crystal X-ray
structure data collections were performed on a Bruker
AXS Kappa Apex II CCD diffractometer with graphite
monochromated Mo Ka radiation (l = 0.71073 Å).
Crystals were coated with paraffin oil (inert), mounted
on a fibre capillary and data were collected at 273 K. The
reflections with I > 2s(I) were employed for structure
solution and refinement. The SIR92 [18] (WINGX32)
X-ray structure determination
Single crystal X-ray diffraction data of 1–5 were
collected by the selection of appropriate suitable single
crystals which are formed by the vapor diffusion method
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 7–10

8
R. SOMAN ET AL.
Fig. 7. (a) Orthogonal arrangement of 4 through (ph)C-H∙∙∙C(ph) interaction viewed along ‘bc’ plane; (b) slip-stack or off-set fashion
of 5 viewed down ‘a’ axis
Fig. 8. (a) Hirshfeld surfaces mapped with (a–e) dnorm ranging from -0.40 Å (red) to 2.50 Å (blue); (f–j) 2D fingerprint plots with di
and de ranging from 1.0 to 2.8 Å for 1–5
Fourier syntheses led to the location of all of the non-
hydrogen atoms. For the structure refinement, all data
were used including negative intensities. The criterion of
F2 > 2s(F2) was employed for calculating R1. R factors
based on F2(wR2) are statistically about twice as large as
those based on F, and R factors based on all data will
be even larger. Non-hydrogen atoms were refined with
anisotropic thermal parameters. All of the hydrogen
atoms in the porphyrin structure could be located in
the difference map. However, the hydrogen atoms
were geometrically relocated at chemically meaningful
positions and were given riding model refinement.
Fig. 9. Percentage distribution of individual intermolecular
interactions on the basis of Hirshfeld surface analysis of 1–5
Hirshfeld surface analysis
program was used for solving the structure by direct
methods. Successive Fourier synthesis was employed
to complete the structures after full-matrix least squares
refinement on |F|2 using the SHELXL97 [19] software.
We analyzed the crystal structures by Hirshfeld
surface analysis (HSs) and 2D fingerprint plots (FPs)
using Crystal Explorer 3.1 [16] based on results of
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 8–10

STRUCTURAL ELUCIDATION AND STUDY OF INTERMOLECULAR INTERACTIONS IN meso-TETRATOLYLPORPHYRINS
9
single crystal X-ray diffraction studies. The function
dnorm is a ratio of distances of any surface point to the
nearest interior (di) and exterior (de) atom and the van
der Waals radii of the atoms [20]. The negative value of
dnorm indicates the sum of di and de is shorter than the sum
of the relevant van der Waals radii, which is considered
to be a closest contact and is envisaged by the red color
in the Hirshfeld surfaces. The white color denotes
intermolecular distances close to van der Waals contacts
with dnorm equal to zero whereas contacts longer than the
sum of van der Waals radii with positive dnorm values are
colored with blue. A plot of di vs. de is a 2D fingerprint
plot which recognizes the existence of different types of
intermolecular interactions.
(CCDC) under numbers CCDC-1041763, 956522,
1058016, 1041764 and 980778. Copies can be obtained
on request, free of charge, via www.ccdc.cam.ac.uk/
data_request/ cif or from the Cambridge Crystallographic
Data Center, 12 Union Road, Cambridge CB2 1EZ, UK
(fax: +44 1223-336-033 or email: data_request@ccdc.
cam.ac.uk).
REFERENCES
1. Milgrom LR. The colors of life: An introduction to
the chemistry of porphyrins and related compounds,
Oxford University Press: New York, 1997.
2. Senge MO. In The Porphyrin Handbook, Vol. 1,
Kadish KM, Smith KM and Guilard R. (Eds.), Aca-
demic Press: San Diego, CA, 1999; p. 239.
3. Shelnutt JA, Song X-Z, Ma J-G, Jia S-L, Jentzen W
and Medforth CJ. Chem. Soc. Rev. 1998; 27: 31–42
and references therein.
4. Sheldon RA. Metalloporphyrins in Catalytic Oxi-
dations, Marcel Dekker Inc: New York, 1994.
5. Parusel ABJ, Wondimagegn T and Ghosh A. J. Am.
Chem. Soc. 2000; 122: 6371–6374.
CONCLUSION
In summary, we performed the structural elucidation
and study of various intermolecular interactions of meso-
tetratolylporphyrins, 1–5 using single crystal X-ray
diffraction studies combined with computational Hirshfeld
surface analysis. Our results reveal that the planar systems,
1, 3 and 4 are packed in a “orthogonal fashion” possessing
intermolecular interaction mainly of (ph)C–H∙∙∙C(ph) which
is in the range of ~2.81 Å whereas the crystal packing
of non-planar systems, 2 and 5 in a “slip-stack or off-set
fashion” through various intermolecular interactions. The
non-planar porphyrin, 2 exhibits saddle geometry whereas
5 showed a domed geometry as evident from the single
crystal X-ray diffraction studies. The enhancement of
non-planarity in 2 is presumably due to the presence of
various intermolecular interactions caused by the presence
of CF3COO- anions on both faces of the porphyrin in
addition to the bulky bromine groups at the b-pyrrole
positions. In 5, the non-planarity is merely due to the metal
coordination at the porphyrin core as pentacoordinated
MnIII centre with a chloro ligand in the axial position. The
Hirshfeld surface analysis of porphyrins 1–5 indicates
that the crystal packing is mainly stabilized by the close
contacts involving C∙∙∙H [28% in 1; 26% in 3; 12% in 4] and
H∙∙∙H [64% in 1; 48% in 3; 52% in 4] in planar porphyrins;
whereas in non-planar porphyrins, in addition to the above
major interactions, the close contacts involving halogens
H∙∙∙F/Cl/Br [24% in 2; 15% in 5] also play a major role in
the formation of supramolecular network.
6. Song X-Z, Jentzen W, Jia S-L, Jaquinod L, Nurco
DJ, Medforth CJ, Smith KM and Shelnutt JA.
J. Am. Chem. Soc. 1996; 118: 12975–12988.
7. Senge MO, Ema T and Smith KM. J. Chem. Soc.,
Chem. Commun. 1995; 733–734.
8. (a) Sujatha S and Arunkumar C. In Fluorinated
Porphyrinic Crystalline Solids: Structural Eluci-
dation and Study of Intermolecular Interactions,
Crystalline and Non-crystalline Solids, Mandracci
P. (Ed.) InTech Publishers: (ISBN 978-953-51-
4721-3) — Open Science Open Minds, 2016; ch. 4,
pp. 57–78. (b) Soman R, Sujatha S, De S, Rojisha
VC, Parameswaran P, Varghese B and Arunku-
mar C. Eur. J. Inorg. Chem. 2014; 2653–2662.
(c) Soman R, Sujatha S and Arunkumar C. J. Fluor.
Chem. 2014; 163: 16–22. (d) Kooriyaden FR,
Sujatha S, Varghese B and Arunkumar C. J. Fluor.
Chem. 2015; 170: 10–16.
9. Lindsey JS, Schreiman IC, Hsu HC, Kearney PC
and Marguerettaz AM. J. Org. Chem. 1987; 52:
827–836.
10. (a) Callot HJ. Tetrahedron Lett. 1973; 14: 4987–
4990. (b) Callot HJ. Bull. Soc. Chim. Fr. 1974; 7–8:
1492. (c) Crossley MJ, Burn PL, Chew SS, Cuttance
FB and Newsom IA. J. Chem. Soc. Chem. Commun.
1991; 1564–1566. (d) Terazono Y, Patrick BO and
Dolphin DH. Inorg. Chem. 2002; 41: 6703–6710.
(e) Kumar PK, Bhyrappa P and Varghese B. Tet-
rahedron Lett. 2003; 44: 4849–4851. (f) Bhy-
rappa P, Velkannan V, Karunanithi K, Varghese B
and Harikrishna. Bull. Chem. Soc. Jpn. 2008; 81:
995–1001.
Acknowledgements
Financial support from DST, New Delhi to CA (SB/
EMEQ-016/2013) is gratefully acknowledged. We would
like to thank Dr. Babu Varghese, SAIF, IIT Madras for
the single crystal data collection, structure solution and
refinement.
Supporting information
Crystallographic data for porphyrins 1–5 have been
deposited at the Cambridge Crystallographic Data Center
11. Adler AD, Longo FR, Kampas F and Kim J.
J. Inorg. Nucl. Chem. 1970; 32: 2443–2445.
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 9–10

10
R. SOMAN ET AL.
12. Bhyrappa P, Arunkumar C and Varghese B. Acta
Cryst. 2008; C64: o276–o278.
Western Australia, 2005–2013; http://hirshfeldsur-
face.net/CrystalExplorer.
13. (a) Dastidar P and Goldberg I. Acta Cryst. 1996;
C52: 1976–1980. (b) McGill S, Nesterov VN and
Gould SL. Acta Cryst. 2010; E66: m723.
14. Scheidt WR, Mondal JU, Eigenbrot CW, Adler A,
Radonovich LJ and Hoard JL. Inorg. Chem. 1986;
25: 795–799.
17. Perrin DD and Armarego WLF. Purification of
organic solvents, Pergamon Press: Oxford, 1988.
18. Altomare AG, Cascarano G, Giacovazzo C and
GualardiA. J. Appl. Crystallogr. 1993; 26: 343–350.
19. Sheldrick GM, SHELXL97; University of Goettin-
gen: Goettingen, Germany, 1997.
15. (a) Bhyrappa P, Arunkumar C and Vittal JJ. J.
Chem. Sci. 2005; 117: 139-143 and references cited
therein. (b) Schauer CK, Anderson OP, Eaton SS
and Eaton GR. Inorg. Chem. 1985; 24: 4082–4086.
16. Wolff SK, Grimwood DJ, McKinnon JJ, Turner MJ,
Jayatilaka D and Spackman MA. Crystal Explorer
3.1 (2013), University of Western Australia, Crawley,
20. (a) Hirshfeld FL. Theor. Chim. Acta 1977; 44:
129–138. (b) Spackman MA and McKinnon JJ.
CrystEngComm. 2002; 4: 378–392. (c) Spackman
MA and Jayatilaka D. CrystEngComm. 2009; 11:
19–32.
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 10–10