Metal complexes of a phenol-tailed porphyrin with different hydrogen bonds

Article abstract of DOI:10.1080/00958972.2016.1206656

Hydrogen bonds are very common and important interactions in biological systems, they are?used to control the microenvironment around metal centers. It is a challenge to develop appropriate models for studying hydrogen bonds. We have synthesized two metal complexes of the phenol-tailed porphyrin, [Zn(HL)] and [Fe(HL)(C₆H₄(OH)(O))]. X-ray crystallography reveals that the porphyrin functions as a dianion HL^2? and the phenol OH is involved in hydrogen bonds in both structures. In [Zn(HL)], an intramolecular hydrogen bond is formed between the carbonyl oxygen and OH. In [Fe(HL)(C₆H₄(OH)(O))], the unligated O(5) of the ligand is involved in two hydrogen bonds, as a hydrogen bond donor and a hydrogen bond acceptor. The overall electronic effect on the ligand could be very small, with negligible impact on the structure and the spin state of iron(III). The structural differences caused by the hydrogen bonds are also discussed.

Full text of DOI:10.1080/00958972.2016.1206656

Journal of Coordination Chemistry
ISSN: 0095-8972 (Print) 1029-0389 (Online) Journal homepage: http://www.tandfonline.com/loi/gcoo20
Metal complexes of a phenol-tailed porphyrin with
different hydrogen bonds
Caifen Ou, Huan Liu, Ben Ma & Chuanjiang Hu
To cite this article: Caifen Ou, Huan Liu, Ben Ma & Chuanjiang Hu (2016) Metal complexes of a
phenol-tailed porphyrin with different hydrogen bonds, Journal of Coordination Chemistry, 69:15,
2308-2317, DOI: 10.1080/00958972.2016.1206656
To link to this article: http://dx.doi.org/10.1080/00958972.2016.1206656
Accepted author version posted online: 27
Jun 2016.
Published online: 12 Jul 2016.
Submit your article to this journal
Article views: 42
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at
http://www.tandfonline.com/action/journalInformation?journalCode=gcoo20
Download by: [University of Newcastle, Australia]
Date: 30 March 2017, At: 22:12

Journal of Coordination Chemistry, 2016
Vol. 69, no. 15, 2308–2317
http://dx.doi.org/10.1080/00958972.2016.1206656
Metal complexes of a phenol-tailed porphyrin with different
hydrogen bonds
Caifen Ou†, Huan Liu†, Ben Ma and Chuanjiang Hu
Key laboratory of organic synthesis of Jiangsu Province, College of Chemistry, Chemical engineering and materials
science, soochow university, suzhou, Pr China
ABSTRACT
ARTICLE HISTORY
received 17 January 2016
accepted 16 may 2016
Hydrogen bonds are very common and important interactions in biological
systems, they are used to control the microenvironment around metal
centers. It is a challenge to develop appropriate models for studying
hydrogen bonds. We have synthesized two metal complexes of the phenol-
tailed porphyrin, [Zn(HL)] and [Fe(HL)(C6H4(OH)(O))]. X-ray crystallography
reveals that the porphyrin functions as a dianion HL2− and the phenol OH is
involved in hydrogen bonds in both structures. In [Zn(HL)], an intramolecular
hydrogen bond is formed between the carbonyl oxygen and OH. In [Fe(HL)
(C6H4(OH)(O))], the unligated O(5) of the ligand is involved in two hydrogen
bonds, as a hydrogen bond donor and a hydrogen bond acceptor. The overall
electronic effect on the ligand could be very small, with negligible impact on
the structure and the spin state of iron(III). The structural differences caused
by the hydrogen bonds are also discussed.
KEYWORDS
Porphyrin; hydrogen bond;
phenol; crystal structure
Introduction
Hydrogen bonds are common in biological systems. They are generally considered as noncovalent
interactions, used to control the microenvironment around metal centers. Porphyrin is a versatile func-
tional group, playing important roles in many biological systems. Hydrogen bonds are widespread in
many heme proteins, such as myoglobin, horseradish peroxidase, cytochrome P450, etc. For example,
hydrogen bonding interactions in myoglobin involve the distal histidine, which can stabilize the iron
CONTACT Chuanjiang hu
cjhu@suda.edu.cn
†these authors contributed equally.
© 2016 informa uK limited, trading as taylor & francis Group

JOurnaL OF COOrdInaTIOn CHeMIsTry
2309
bound oxygen [1]. In horseradish peroxidase [2], there is a strong hydrogen bond between the proximal
histidine (His170) and a highly conserved aspartate group asp247. It is believed that this hydrogen bond
increases the basicity of the His170 proximal ligand, thus stabilizing high oxidation state intermedi-
ates [2(b)]. Hydrogen bonds have also been investigated in many model systems. For example, Walker
et al. reported that forming a hydrogen bond to the nH of coordinated imidazole led to a substantial
increase in the magnitude of the corresponding binding constant [3]. Hu et al. studied the hydrogen
bonding effect on the spin state of five-coordinate iron(II) porphyrinates [4]. Their studies suggest
strong hydrogen bonds to the coordinated ligand could cause different spin states of iron(II). recently,
rath and coworkers studied the impact of hydrogen bonding interactions on the electronic structure
of a five-coordinate iron(III) octaethyltetraarylporphyrin chloride. They found the spin state of iron(III)
switch reversibly between high (S = 5/2) and intermediate spin (S = 3/2) with hydrogen bonds to the axial
ligand [5]. Though there are many model systems developed, it is still a challenge to develop models
for studying hydrogen bonds of ligands.
We have been working on porphyrin-related hydrogen bonds [4, 6], recently synthesizing H3L (shown
in scheme 1) with a hanging phenol group [7]. The free base porphyrin H3L is a triprotonic acid, which
contains two inner nH and one phenol OH. When the porphyrin is metallated, there are two cases: (1) all
three hydrogens are deprotonated to form L3−; (2) two inner nH are deprotonated but the phenol OH is not,
forming HL2−. For the second case, the phenol OH could provide a hydrogen bonding site. If the correspond-
ing hydrogen bonds are associated with the ligand, we are interested in their effect on the structure and
spin state of the metal. Herein, we synthesized two new complexes as shown in scheme 1, one is a zinc(II)
complex, [Zn(HL)] and the other is an iron(III) complex with catechol as axial ligand, [Fe(HL)(C6H4(OH)(O))].
Both have also been characterized by X-ray crystallography and 1H nMr.Their structures reveal that in both
complexes, the porphyrin is HL2− and the phenol OH is involved in different hydrogen bonds.
2. Experimental
2.1. Materials and general methods
H3L and [FeL] were prepared according to our previous method [7]. Other chemicals were used with-
1
out purification. H nMr spectra were recorded on a Bruker aVanCe 400 MHz spectrometer in the
Scheme 1. synthetic route to [Zn(hl)] and [fe(hl)(C6h4(oh)(o))].

2310
C. Ou eT aL.
solvents indicated with tetramethylsilane as the internal standard. uV–vis spectra were measured on
a shimadzu uV-3150 spectrometer. Mass spectra were taken with an agilent 6220 accurate-Mass TOF
LC/Ms. Fluorescence emission spectrum of [Zn(HL)] was measured in toluene on a FLs920 spectrome-
ter. ePr spectrum of polycrystalline sample of [Fe(HL)(C6H4(OH)(O))] was obtained on a eMX 10/12 ePr
spectrometer operating at X band at 25 °C at nanjing university.
2.2. Synthesis of [Zn(HL)]
To a solution of H3L (0.30 g, 0.37 mmol) in chloroform (100 mL), a solution of Zn(Oac)2·2H2O (0.16 g,
0.74 mmol) in methanol (10 mL) was added. The mixture was refluxed for 3 h, then cooled. The mix-
ture was washed with water (3 × 300 mL), the organic layer was separated and dried with anhydrous
na2sO4, then purified with silica gel chromatography (CH2Cl2:petroleum = 3:1 as eluent) to give [Zn(HL)]
(0.29 g, yield 91%). 1H nMr (400 MHz, CdCl3): δ 8.92 (d, 2H), 8.87 (d, 1H), 8.81 (d, 2H), 8.67 (d, 2H), 8.63
(d, 2H), 8.38 (d, 1H), 8.32 (m, 3H), 8.09 (t, 1H), 8.03 (m,4H), 7.79 (m, 3H), 7.70 (m, 4H), 7.65 (m, 2H), 7.49
(t, 1H), 7.18 (d, 1H), 6.07 (t, 1H), 5.83 (t, 1H), 5.76 (d, 1H), 2.94 (d, 1H), 2.05 (s, 1H). LC-esI-Ms: m/z Calcd
for C55H34n4O3Zn 862.19; found 863.20 [M + H]+. uV–vis, nm (ε × 10−3 M−1 cm−1): 428 (538), 557 (20), 598
(5), in CH2Cl2. anal. Calcd for C55H34n4O3Zn⋅1.3CH2Cl2: C, 69.38; H, 3.78; n, 5.75. Found: C, 69.13; H, 3.72;
n, 5.59. X-ray quality crystals were obtained by liquid diffusion of methanol into the toluene solution
in 8 mm diameter glass tubes.
2.3. Synthesis of [Fe(HL)(C6H4(OH)(O))]
[FeL] (40 mg, 0.047 mmol) and catechol (36 mg, 0.33 mmol) were mixed in toluene (4 mL) and stirred
for 30 min at room temperature. X-ray quality crystals were obtained by liquid diffusion of hexane into
1
the toluene solution in 8 mm diameter glass tubes. H nMr (400 MHz, CdCl3): δ 92.78, 89.92, 87.22,
81.16, 79.76, 12.21, 11.98, 11.50, 11.28, 10.78, 10.56, 8.92, 8.56, 8.07, 7.16, 6.75, 6.57, 6.04, 4.47, 103.90,
105.21. uV–vis, nm (ε × 10−3 M−1 cm−1): 327 (34), 421 (110), 501 (11), 564 (5), 647 (4) in CH2Cl2. anal. Calcd
C61H39Fen4O5·3.5H2O: Calcd C, 71.35; H, 4.52; n, 5.46%. Found: C, 71.32; H, 4.46; n, 5.34%.
2.4. X-ray crystallography
X-ray data collections were made on a rigaku Mercury CCd X-ray diffractometer by using graphite
monochromated Mo Kα (λ = 0.071073 nm) radiation at 223(2) K. structures of [Zn(HL)] and [Fe(HL)
(C6H4(OH)(O))] were solved by direct methods and refined on F2 using full matrix least-squares with
sHeLXTL version 97 [8]. all non-hydrogen atoms were refined anisotropically. all hydrogens were ide-
alized with the standard sHeLXL-97 idealization methods. Complete crystallographic details, atomic
coordinates, anisotropic thermal parameters, and hydrogen coordinates are given in the cif file. For
[Fe(HL)(C6H4(OH)(O))], the structure has badly disordered solvate molecules. sQueeZe [9] was used
to model the disordered solvate molecules. The residue electron count in the interporphyrin voids is
73 electrons per unit-cell (corresponding roughly to 0.8 molcules of toluene). a summary of the key
crystallographic information of the complex is given in table 1.
3. Results and discussion
[Zn(HL)] was obtained by reaction of H3L with Zn(Oac)2. The new iron complex [Fe(HL)(C6H4(OH)(O))]
was prepared by reaction of [FeL] with excess catechol.
3.1. Molecular structure
Both complexes have been characterized by X-ray crystallography. Their OrTeP diagrams are presented
in figures 1 and 2. The crystal structure of [Zn(HL)] was solved in P21/c space group. One asymmetric

JOurnaL OF COOrdInaTIOn CHeMIsTry
2311
Table 1. Crystallographic data for [Zn(hl)]⋅Ch2Cl2 and [fe(hl)(C6h4(oh)(o))].
Compound
[Zn(HL)]⋅CH2Cl2
[Fe(HL)(C6H4(OH)(O))]
empirical formula
formula weight (g mol−1
temperature (K)
Wavelength
Crystal system
space group
C56h36Cl2n4o3Zn
949.16
223(2)
0.71073
monoclinic
P21/c
C61h39fen4o5
963.81
223(2)
0.71073
triclinic
)
P-1
unit cell dimensions
a = 20.295(4) Å
b = 11.429(2) Å
c = 23.118(10) Å
α = 90°
a = 11.197(3) Å
b = 13.209(3) Å
c = 20.223(5) Å
α = 107.126(5)°
β = 95.400(5)°
γ = 91.023(3)°
2842.5(12)
2
β = 122.42(2)°
γ = 90°
Volume (Å3)
4526(2)
4
1.393
1952
0.50 × 0.40 × 0.30
3.02°–25.00°
−22 ≤ h ≤ 24
−13 ≤ k ≤ 12
−27 ≤ l ≤ 19
21,653/7946
99.6%
Z
ρ (g cm−3
F (0 0 0)
)
1.126
998
Crystal size (mm3)
0.60 × 0.50 × 0.40
3.02°–25.00°
−13 ≤ h ≤ 13
−15 ≤ k ≤ 15
−24 ≤ l ≤ 24
21,059/9876
98.5%
theta range for data collection
limiting indices
reflections collected/unique
Completeness to θ = 25.00°
data/restraints/parameters
Gof
7946/22/538
1.129
9876/0/630
1.028
R1, wR2[>2σ(I)]
R1 = 0.0791
wR2 = 0.2038
R1 = 0.1120
wR2 = 0.2341
0.923 and −0.805
R1 = 0.0662
wR2 = 0.1970
R1 = 0.0801
wR2 = 0.2122
0.996 and −0.362
R1, wR2 (all data)
largest diff. peak and hole (e Å−3
)
aw = 1/[σ2 (Fo2) + (aP)2 + bP] where P = (Fo2 + 2Fc2).
O(2)
C(1)
O(1)
H(3)
O(3)
C(B8)
C(B7)
C(M1)
N(1)
N(2)
N(4)
N(3)
C(B5)
C(A3)
C(B3)
Zn(1)
C(A4)
C(B6)
C(M2)
C(B4)
Figure 1. orteP view for [Zn(hl)] at 50% probability thermal ellipsoids. the hydrogens except h(3) and two phenyl groups have
been omitted for clarity.
unit contains one porphyrin and one methylene chloride molecule. There are one naphthyl and three
phenyl groups at the meso-positions of the porphyrin. The phenol group is covalently bonded to the
porphyrin at the eight-position of naphthyl group. Zinc(II) is five-coordinate with four pyrrole nitrogens
and one phenol oxygen. since there is no ion in the crystal structure, the porphyrin complex is neutral.

2312
C. Ou eT aL.
Figure 2. orteP view for [fe(hl)(C6h4(oh)(o))] at 50% probability thermal ellipsoids. the hydrogens (except h(3o) and h(5o)) and
two phenyl groups have been omitted for clarity.
Corresponding to zinc(II), the porphyrin should be the dianion, HL2−, in order to maintain neutrality.
Obviously, the two inner nH groups are deprotonated, then four pyrrole nitrogens are coordinated to
zinc. The axial ligand is from the phenol tail in which oxygen is protonated.
selected bond distances are listed in table 2. The Zn–O distance is 2.368(4) Å and the average Zn–
np distance is 2.041(16) Å; these values are similar to that in the reported 4-chlorophenol ligated zinc
porphyrinate [10]. Zinc is out of the porphyrin plane with a displacement of 0.17 Å, which is also typical
for five-coordinate zinc porphyrinates.
The OH is not only coordinated to zinc, but also functions as a hydrogen donor to form an intra-
molecular hydrogen bond with the carbonyl O(1). The corresponding O⋯O distance is 2.660 Å and
the O–H⋯O angle is 152.3°, while the corresponding O⋯O distance is much longer in H3L (4.575 Å) or
[FeL] (2.936 Å) when there is no hydrogen bond between these two oxygens.
For [Fe(HL)(C6H4(OH)(O))], the crystal structure was solved in the P-1 space group. Iron is five-coor-
dinate with four pyrrole nitrogens and one oxygen. different from [FeL], the axial ligand is from the
catechol, not the covalent bonded phenol.
The coordinated catechol is on the same side as the phenol tail with the crystal structure revealing
that hydrogen bonds contribute to this geometry. The catechol is bonded to iron by the deprotonated
O(4) and behaves as a −1 charged ion. Corresponding to iron(III), the porphyrin moiety should be HL2−
.
so there is one OH group for either the catechol or the tailed phenol. Both OH groups are involved
in hydrogen bonds. as shown in figure 3, the uncoordinated catechol O(5) is involved in two types
of hydrogen bonds in the crystal structure: (1) one is an intramolecular hydrogen bond formed with
carbonyl O(1); (2) another is an intermolecular hydrogen bond formed with the tailed phenol OH from
Table 2. selected bond lengths (Å) and angles (°) for [Zn(hl)] and [fe(hl)(C6h4(oh)(o))].
[Zn(hl)]
Zn(1)–n(1)
Zn(1)–n(3)
Zn(1)–o(1)
C(1)–o(2)
2.040(4)
2.019(4)
2.368(4)
1.333(6)
Zn(1)–n(2)
Zn(1)–n(4)
C(1)–o(3)
2.048(4)
2.057(4)
1.208(6)
[fe(hl)(C6h4(oh)(o))]
fe(1)–n(1)
fe(1)–n(3)
fe(1)–o(4)
C(1)–o(2)
2.073(2)
2.078(2)
1.835(2)
1.344(5)
fe(1)–n(2)
fe(1)–n(4)
C(1)–o(1)
2.080(3)
2.077(2)
1.185(5)

JOurnaL OF COOrdInaTIOn CHeMIsTry
2313
Figure 3. Packing diagram showing hydrogen bonds in [fe(hl)(C6h4(oh)(o))]. symmetry transformations used to generate equivalent
atoms: a −x + 2, −y + 2, −z + 2.
the neighboring porphyrin unit. The corresponding distances and angles are listed in table 3. These
hydrogen bonds cause porphyrin molecules to form dimers in the solid state. different from rath’s
case [5], the coordinated O(4) is not involved in hydrogen bonds. so the hydrogen bond is far from
the metal center.
For this new iron(III) complex, selected bond distances are listed in table 2. The average Fe−np dis-
tance (2.077(3) Å), Fe−O distance (1.835(2) Å) and the displacement of iron out of the porphyrin plane
(0.48 Å) are similar to values for [FeL]. The Fe−np distance and the displacement of iron are much larger
than those in five-coordinate low-spin iron(III) porphyrinates but typical for five-coordinate high-spin
iron(III) porphyrinates [11]. The above structural feature suggests [Fe(HL)(C6H4(OH)(O))] is a high-spin
iron(III) species as was [FeL]. such spin state is also confirmed by nMr spectroscopy.
O(5) of the ligand is involved in two hydrogen bonds, a hydrogen bond donor in one and a hydrogen
acceptor in the other. so the net electronic effect on the catechol could be very small, with negligible
impact on the structure and the spin state of iron(III).
We are also interested in the structural differences caused by coordination bonds and hydrogen
bonds. For both [FeL] and [Zn(HL)], the ligand is from the covalent bonded phenol group, causing the
overall structure to be strained, such as the tilted M–O bond and the displacement of the meso carbon
(C(m1)) out of the porphyrin plane. The tilted angle is the angle between M–O bond and the normal
direction of porphyrin. For [Fe(HL)(C6H4(OH)(O))], the Fe–O bond is almost perpendicular to the heme
plane, with a very small angle between Fe–O and the normal direction of porphyrin (2.5°). But the corre-
sponding angle is 7.5° for [FeL] and 12.2° for [Zn(HL)]. such tilt is caused by the constraint due to covalent
bonding of phenol to the porphyrin. another result of the constraint is the positive displacement of
meso-carbon (C(m1)) out of the porphyrin plane. The displacement is 0.09 Å for [Zn(HL)] and 0.23 Å
Table 3. Bond lengths (Å) and angles (°) for hydrogen bonds in [fe(hl)(C6h4(oh)(o))].
d–H⋯a
d(d–H)
d(H⋯a)
d(d⋯a)
<(dHa)
o(5)–h(5o)⋯o(1)
o(3)–h(3o)⋯o(5a)
0.83
0.83
2.18
2.08
2.855(4)
2.717(4)
138.2
133.6
note: symmetry transformations used to generate equivalent atoms: a −x + 2, −y + 2, −z + 2.

2314
C. Ou eT aL.
Table 4. dihedral angles (°) between the Coo plane and four nitrogen porphyrin plane (or covalently bonded phenyl plane).
Four-nitrogen plane
Covalently bonded phenyl plane
Coo plane
h3l
[fel]
24.6
23.7
19.4
31.0
44.1
55.2
37.5
76.6
[Zn(hl)]
[fe(hl)(C6h4 (oh)(o))]
for [Fe(HL)], towards the carboxylate group. For [Fe(HL)] without such constraint, the corresponding
displacement is −0.10 Å, away from the carboxylate group.
For these compounds, hydrogen bonds cause different dihedral angles between the COO plane
and porphyrin plane (or the covalently bonded phenyl plane) as shown in table 4. For H3L and [FeL],
the corresponding dihedral angles between the COO group and four-nitrogen porphyrin plane are
24.6° and 23.7°, respectively. These angles are close to that in enTPP (23.2°) [12]. But for [Zn(HL)], due
to the intramolecular hydrogen bond between O(1) and coordinated O(3), the corresponding angle
decreases to 19.4°. such hydrogen bond also causes the dihedral angle between the COO plane and
the covalently bonded phenyl plane to be much smaller in [Zn(HL)]. For [Fe(HL)], O(1) is hydrogen
bonded to O(5), the uncoordinated atom, which causes the corresponding dihedral angle to be much
larger (31.0°), not smaller.
notably, the orientation of the tailed phenol plane in [Fe(HL)(C6H4(OH)(O))] is also different from
others. For [Zn(HL)], the dihedral angle between the porphyrin plane and the phenol plane is 29.3°,
similar to H3L and [FeL]. But for [Fe(HL)(C6H4(OH)(O))], since the coordinated catechol is on the same side
as the tailed phenol, the covalent bonded phenol forms a dihedral angle of 88.1° with the porphyrin
plane, much greater than in the other cases. such orientation also causes the tailed phenyl to form a
dihedral angle of 18.95° with the coordinated catechol. The corresponding centroid to centroid distance
is 4.43 Å, which indicates there is a weak offset π–π interaction between the coordinated catechol and
the tailed phenol [13].
3.2. 1H NMR studies
The 1H nMr of [Zn(HL)] is shown in figure 4(b). since the phenol is located above the porphyrin plane,
the ring current effect will generally cause their signals to shift upfield [14]. For the case of H3L [7], these
protons are located at 2.54, 3.41 and 5.43 ppm as shown in figure 4(a). Compared with them, the signals
at 6.07, 5.83, 5.76 and 2.94 ppm with 1:1:1:1 ratio for [Zn(HL)] are assigned to the CH proton of the
substituted phenol. For [Zn(HL)], the signal of OH is at 2.05 ppm. But for H3L, there are no observable
signals for OH and nH protons. One possible reason is that fast exchange occurs between them. similar
case has also been reported by Liang et al. [15].
1H nMr spectrum of [Fe(HL)(C6H4(OH)(O))] is shown in figure 4(d). In this case, since iron(III) is para-
magnetic, the signals are broader and expanded. The spectrum also shows resonances in the far-upfield
and far-downfield region. similar to those of [FeL] [7] (figure 4(c)), the signals at 79.76 and 87.22 ppm
are assigned to the pyrrole protons according to their positions and intensities, which are typical for
five-coordinate high-spin (tetraphenylporphyrinato)iron(III) complex [16]. Besides those pyrrole proton
signals, there are also resonances at 89.92 and −105.21 ppm. Compared with those in phenolate (por-
phyrinate)iron(III) complexes [16], the far-downfield resonance at 89.92 ppm is assigned to meta-protons
(Hb and Hd) of the coordinated phenol group, the far-upfield resonances at −105.21 ppm are assigned
to ortho- and para-protons (Ha and Hc). so the 1H nMr spectrum suggests that [Fe(HL)(C6H4(OH)(O))]
has the same spin state as [FeL]. For the new iron complex, there are also extra peaks in the far-upfield
and far-downfield region, which could be caused by the uncoordinated phenol ring.
3.3. Fluorescence spectrum
The fluorescence spectrum of [Zn(HL)] was measured in toluene. as shown in figure 5, there
are two absorption peaks at 602 and 649 nm in the emission spectrum. Compared with those for

JOurnaL OF COOrdInaTIOn CHeMIsTry
2315
Figure 4. 1h nmr spectra of (a) h3l, (b) [Zn(hl)], (c) [fel] and (d) [fe(hl)(C6h4(oh)(o))] in CdCl3. *, signal from impurity of grease.
Figure 5. fluorescence emission spectrum of [Zn(hl)] in toluene. Concentration: 2.0 × 10−7 mol l−1. excitation wavelength: 425 nm.

2316
C. Ou eT aL.
Figure 6. X-band ePr spectrum of polycrystalline sample of [fe(hl)(C6h4(oh)(o))] at 25 °C.
tetraphenylporphyrin [17], these peaks are blue-shifted. These positions are similar to those in some
other zinc porphyrinates containing phenols as axial ligands [18], which suggest that [Zn(HL)] is coor-
dinated by phenol in solution. It is consistent with the 1H nMr results.
3.4. EPR study
The spin state of the Fe(III) in [Fe(HL)(C6H4(OH)(O))] is further confirmed by ePr spectrum. The spectrum
was recorded at room temperature. as shown in figure 6, though the signal-to-noise ratio was not very
good, the spectrum clearly showed the feature at g = 5.2, which is a typical value for high-spin Fe(III)
heme, similar to those for the reported Fe(III) heme [19]. The result is consistent with its structure and
1H nMr results.
4. Conclusion
We have synthesized and characterized two new complexes of the phenol-tailed porphyrin, [Zn(HL)] and
[Fe(HL)(C6H4(OH)(O))]. X-ray crystal structures reveal the porphyrins function as dianions and the phenol
OH is hydrogen bonded in both complexes. different hydrogen bonds cause different orientations of
the tailed phenol group. For [Fe(HL)(C6H4(OH)(O))], the unligated O(5) of the ligand plays double roles
in two hydrogen bonds, one as a hydrogen bond donor and another as a hydrogen bond acceptor. The
overall contribution on the ligand is small, causing negligible impact on the structure and the spin state
of iron(III). Our studies confirm the tailed phenol forms hydrogen bonds with the axial ligand. Further
studies on other ligands are ongoing.
Supplementary material
CCdC 1426124 and 1426126 contain the supplementary crystallographic data. These data can be obtained free of charge
via www.ccdc.cam.ac.uk/conts/retrieving.html or by application to the director, CCdC, 12 union road, Cambridge CB2
1eZ, uK; Fax: (+44) 1223 336 033; e-mail: deposit@ccdc.cam.ac.uk.
Disclosure statement
no potential conflict of interest was reported by the authors.
Funding
This work was supported by the natural science Foundation of China [grant number 21271133]; state and Local Joint
engineering Laboratory for novel Functional Polymeric Materials; the Priority academic Program development of Jiangsu
Higher education Institutions.

JOurnaL OF COOrdInaTIOn CHeMIsTry
2317
References
[1] (a) K.d. egeberg, B.a. springer, s.a. Martinis, s.G. sligar, d. Morikis, P.M. Champion. Biochemistry, 29, 9783 (1990); (b)
s. adachi, s. nagano, K. Ishimori, y. Watanabe, I. Morishima, T. egawa, T. Kitagawa, r. Makino. Biochemistry, 32, 241
(1993); (c) B.a. springer, s.G. sligar, J.s. Olson, G.n. Phillips Jr. Chem. Rev., 94, 699 (1994); (d) G.d. depillis, s.M. decatur,
d. Barrick, s.G. Boxer. J. Am. Chem. Soc., 116, 6981 (1994).
[2] (a) M. Gajhede, d.J. schuller, a. Henriksen, a.T. smith, T.L. Poulos. Nat. Struct. Biol., 4, 1032 (1997); (b) G.I. Berglund,
G.H. Carlsson, a.T. smith, H. szöke, a. Henriksen, J. Hajdu. Nature, 417, 463 (2002).
[3] F.a. Walker, M.-W. Lo, M.T. ree. J. Am. Chem. Soc., 98, 5552 (1976).
[4] (a) C. Hu, B.C. noll, P.M. Piccoli, a.J. schultz, C.e. schulz, W.r. scheidt. J. Am. Chem. Soc., 130, 3127 (2008); (b) C. Hu,
C.d. sulok, F. Paulat, n. Lehnert, a.I. Twigg, M.P. Hendrich, C.e. schulz, W.r. scheidt. J. Am. Chem. Soc., 132, 3737 (2010).
[5] d. sahoo, M.G. Quesne, s.P. de Visser, s.P. rath. Angew. Chem. Int. Ed., 54, 4796 (2015).
[6] (a) W. Huang, J. Jiang, Z. Feng, X. Kai, C. Hu, H. yu, W. yang. J. Coord. Chem., 64, 2101 (2011); (b) J. Jiang, Z. Feng, B.
Liu, C. Hu, y. Wang. Dalton Trans., 42, 7651 (2013); (c) J. Jiang, X. Fang, B. Liu, C. Hu. Inorg. Chem., 53, 3298 (2014).
[7] B. Ma, J. Jiang, C. Hu. Z. Anorg. Allg. Chem., 639, 676 (2013).
[8] G.M. sheldrick. SHELXL-97, Program for Crystal Structure Refinement, university of Göttingen, Germany (1997).
[9] a.L. spek. J. Appl. Crystallogr., 36, 7 (2003).
[10] M.P. Byrn, C.J. Curtis, y. Hsiou, s.I. Khan, P.a. sawin, s.K. Tendick, a. Terzis, C.e. strouse. J. Am. Chem. Soc., 115, 9480
(1993).
[11] (a) W.r. scheidt, M.G. Finnegan. Acta Crystallogr., Sect. C, 45, 1214 (1989); (b) T. Ikeue, y. Ohgo, a. uchida, M. nakamura,
H. Fujii, M. yokoyama. Inorg. Chem., 38, 1276 (1999); (c) r.a. Ghiladi, r.M. Kretzer, I. Guzei, a.L. rheingold, y.M. neuhold,
K.r. Hatwell, a.d. Zuberbuhler, K.d. Karlin. Inorg. Chem., 40, 5754 (2001); (d) B. song, K. Park, B. yu. J. Kor. Chem. Soc.,
41, 495 (1997); (e) M.O. senge. Acta Crystallogr., Sect. E, 61, m399 (2005).
[12] J. yang, J. Jiang, W. Fang, X. Kai, C. Hu, y. yang. J. Porph. Phthal., 15, 197 (2011).
[13] M.d. Curtis, J. Cao, J.W. Kampf. J. Am. Chem. Soc., 126, 4318 (2004).
[14] C.J. Medforth. In The Porphyrin Handbook, K. Kadish, K. smith, r. Guilard (eds.), Vol. 5, Chap. 35, pp. 1–80, academic
Press, new york, ny (2000).
[15] y. Liang, C.K. Chang, s.-M. Peng. J. Mol. Recognit., 9, 149 (1996).
[16] (a) H.M. Goff, e.T. shimomura, y.J. Lee, W.r. scheidt. Inorg. Chem., 23, 315 (1984); (b) e.W. ainscough, a.W. addison,
d. dolphin, B.r. James. J. Am. Chem. Soc., 100, 7585 (1978); (c) H. sugimoto, n. ueda, M. Mori. Bull. Chem. Soc. Jpn., 55,
3468 (1982); (d) H. nasri, J. Fischer, r. Weiss, e. Bill, a. Trautwein. J. Am. Chem. Soc., 109, 2549 (1987); (d) a.M. Helms,
W.d. Jones, G.L. Mclendon. J. Coord. Chem., 23, 351 (1991); (e) n. ueyama, n. nishikawa, y. yamada, T. Okamura,
a. nakamura. Inorg. Chim. Acta, 283, 91 (1998); (f) d. Kanamori, y. yamada, a. Onoda, T. Okamura, s. adachi,
H. yamamoto, n. ueyama. Inorg. Chim. Acta, 358, 331 (2005); (g) a. Chaudhary, r. Patra, s.P. rath. Eur. J. Inorg. Chem.,
33, 5211 (2010); (h) G. Peychal-Heiling, G.s. Wilson. Anal. Chem., 43, 550 (1971).
[17] G. Peychal-Heiling, G.s. Wilson. Anal. Chem., 43, 550 (1971).
[18] G.d. Bajju, s. Kundan, M. Bhagat, d. Gupta, a. Kapahi, G. devi. Bioinorg. Chem. Appl., 2014, 782762 (2014). doi:http://
dx.doi.org/10.1155/2014/782762.
[19] (a) M.r. Cheesman, V.s. Oganesyan, n.J. Watmough, C.s. Butler, a.J. Thomson. J. Am. Chem. Soc., 126, 4157 (2004);
(b) e.L. Bominaar, X.-Q. ding, a. Gismelseed, e. Bill, H. Winkler, a.X. Trautwein, H. nasri, J. Fischer, r. Weiss. Inorg.
Chem., 31, 1845 (1992).