Synthesis, crystal structure and properties of two novel ferrocenophane compounds

Article abstract of DOI:10.1080/15421406.2017.1396862

The title compounds were synthesized via click reaction. They were characterized by IR, ¹H-NMR, elemental analysis, UV, fluorescence in solution were also applied to characterise their photophysical characterization and single-crystal X-ray diffraction analysis. 1,1′-Ferrocene-dicarboxyl-{[(3-methylphenyl)-imino]di-2,1-ethanediyl} 1 (C₂₃H₂₃FeNO₄) crystallizes in the monoclinic system, with a = 7.4261(13), b = 29.911(5), c = 9.8426(13) ?, α = 90°, β = 118.251(10)°, γ = 90°, V = 1925.8(5) ?^3, 1,1′-Ferrocene-dicarboxyl-{[(2-methylphenyl)-imino]di-2,1-ethanediyl} 2 (C₂₃H₂₃FeNO₄) crystallizes in the monoclinic system, with a = 15.4000 (15), b =7.9007 (8), c = 16.0776 (15) ?, α = 90°, β = 94.266 (2)°, γ = 90°, V = 1950.8 (3)? ³, Both 1 and 2 form 3D net structures, which are further linked to form 3D supramolecular net structures via intermolecular C?H···O, C?H···π and C?H···C stacking interactions, respectively. Fluorescent and UV-vis absorption spectra were also investigated.

Full text of DOI:10.1080/15421406.2017.1396862

Molecular Crystals and Liquid Crystals
ISSN: 1542-1406 (Print) 1563-5287 (Online) Journal homepage: http://www.tandfonline.com/loi/gmcl20
Synthesis, crystal structure and properties of two
novel ferrocenophane compounds
Xiaoju Liu, Liguo Gao, Guoyu Ren, Yajun Ma, Jian Li & Biao Yan
To cite this article: Xiaoju Liu, Liguo Gao, Guoyu Ren, Yajun Ma, Jian Li & Biao Yan (2017)
Synthesis, crystal structure and properties of two novel ferrocenophane compounds, Molecular
Crystals and Liquid Crystals, 658:1, 131-139, DOI: 10.1080/15421406.2017.1396862
To link to this article: https://doi.org/10.1080/15421406.2017.1396862
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MOLECULAR CRYSTALS AND LIQUID CRYSTALS
, VOL. , –
https://doi.org/./..
Synthesis, crystal structure and properties of two novel
ferrocenophane compounds
Xiaoju Liu, Liguo Gao, Guoyu Ren, Yajun Ma, Jian Li, and Biao Yan
Key Laboratory of Synthetic and Natural Chemistry of the Ministry of Education, Chemical Engineering Institute,
the Yu-Lin University of Yulin, Yulin, Shaanxi Province, People’s Republic of China
ABSTRACT
KEYWORDS
Crystal structure;
ferrocenophane; UV-vis and
fluorescent
Thetitlecompoundsweresynthesizedviaclickreaction. Theywerechar-
acterized by IR, 1H-NMR, elemental analysis, UV, fluorescence in solution
were also applied to characterise their photophysical characterization
and single-crystal X-ray diffraction analysis. 1,1ꢀ-Ferrocene-dicarboxyl-
{[(3-methylphenyl)-imino]di-2,1-ethanediyl} 1 (C23H23FeNO4) crystallizes
in the monoclinic system, with a = 7.4261(13), b = 29.911(5), c = 9.8426(13)
3,
A, α = 90°, β = 118.251(10)°, γ = 90°, V = 1925.8(5) A 1,1ꢀ-Ferrocene-
dicarboxyl-{[(2-methylphenyl)-imino]di-2,1-ethanediyl} 2 (C23H23FeNO4)
crystallizes in the monoclinic system, with a = 15.4000 (15) , b =7.9007
˚
˚
˚
˚
(8) , c = 16.0776 (15) A, α = 90°, β = 94.266 (2)°, γ = 90°, V = 1950.8 (3)A
3, Both 1 and 2 form 3D net structures, which are further linked to form
–
–
3D supramolecular net structures via intermolecular C H···O, C H···π
–
and C H···C stacking interactions, respectively. Fluorescent and UV-vis
absorption spectra were also investigated.
Introduction
Synthesis and applications of ferrocene derivatives as ligands have been reported extensively.
Many specific ligands containing O, S or/and N atoms [1–3] in their structures in order to
have high transition metal coordination ability, were previously reported for chemical sensor,
homogeneous catalysts, and conformationally switchable materials [4–9], Now we report two
new ferrocenophane compounds which have well-defined structures.
Experimental
The title compounds 1 and 2 were obtained by esterification (purity: 99%). according to the
following method. 1,10-Ferrocene-di(carbonyl chloride) (1.0 g, 3 mmol) were added drop-
wise over 8 h to a stirring mixture of The dihydric alcohols (3 mmol), 800 mL of dry DCM,
and 0.5 mL (6 mmol) of pyridine at room temperature. The mixture was stirred for one day at
room temperature and then refluxed for another 4 h (monitored by thin-layer chromatogra-
phy, TLC). About 700 mL of the solvent was evaporated, and the residual solution was washed
with 50 mL of water three times and dried over anhydrous MgSO4. After filtered, the solvent
CONTACT Xiaoju Liu
liuxiaoju@.com
Key Laboratory of Synthetic and Natural Chemistry of the Ministry of
Education, Chemical Engineering Institute, the Yu-Lin University of Yulin, Chongwen Avenue , Yulin , Shaanxi Province,
People’s Republic of China.
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/gmcl.
©  Taylor & Francis Group, LLC

132
X. LIU ET AL.
was removed to leaving a crude product. Column chromatography on silica gel (petroleum
ether: ethyl acetate: dichloromethane = 8:2:1) afforded ester ferrocenophane (Scheme 1).
Single crystals of (I) and (II) suitable for X-ray diffraction studies were grown directly by
slow evaporation of 10 ml of the maturated neat CH2Cl2/EtOAc (1/4 v/v) solution of either 1
or 2 on a microscope slide.
O
R
R
O
O
1
2
Py, CH Cl
CH COCl
NaClO
ClCOCOCl
Py, CH Cl
2
2
3
Fe
Fe
N
dihydric alcohols
AlCl , CH Cl
2
2
2
3
2
O
1 R =H R =CH
3
1
2
2 R =CH R =H
1
3
2
Scheme . Synthetic route for the title compounds [, ].
Compound 1
Red solid (45%).m.p. 165–166°C. 1H NMR(CDCl3) δ: 7.17(m, 1H, aromatic), 6.63 m(m, 3H,
aromatic), 4.70(m, 4H, Fc-H), 4.50(t, 4H, (-O-CH2-)), 4.47(m, 4H, Fc-H), 3.74(t, 4H, (-N-
CH2-)), 2.34(s, 3H, (-CH3-)).IR (KBr) υ: 3427, 3098, 2927, 1719, 1597, 1497,1467, 1383, 1283,
1153, 1036, 921, 834, 766, 686, 597,544, 506, 486, 435 cm−1. Anal. Calcd of C23H23FeNO4:
calcd. C 63.76, H 5.35; found C 61.89, H 5.25. MALDI-TOP MS m/z = 434[M+H]+.
Compound 2
1
Yellow solid (38%).m.p. 150–151°C. H NMR(CDCl3) δ: 7.26(m, 3H, aromatic), 7.09 m
(m, 1H, aromatic), 4.81(m, 4H, Fc-H), 4.51(m, 4H, Fc-H), 4.30(t, 4H, (-O-CH2-)), 3.41(t,
4H, (-N-CH2-)), 2.50(s, 3H, (-CH3-)). IR (KBr) υ: 3430, 3100, 2922, 1723, 1626, 1578, 1461,
1374, 1279, 1147, 1027, 917, 825, 763, 730, 604, 535, 472 cm−1. Anal. Calcd of C23H23FeNO4:
calcd. C 63.76, H 5.35; found C 61.89, H 5.25. MALDI-TOP MS m/z = 434[M+H]+.
Results and discussion
Compounds 1 and 2 crystallize in different space groups, P21/c and P21/n. The molecular
structures of 1 and 2 with atomic numbering scheme are presented in Fig. 1. Traditional
hydrogen bonding interactions (such as O-H···O) are not observed in compound 1 and 2
for the hydroxyl H atom, and the absence of such bonding could be attributed to steric and
electronic effects. The ultima supramolecule formed due to the synergic effects of these weak
interactions. Interestingly, the aggregate is neither traditional J- nor H-aggregates. In fer-
rocene, the cyclopentadiene(Cp) rings are parallel to each others, but in 1 and 2 the (Cp) rings
˚
are almost parallel with the average deviations from the least-squares planes of 5.02 and 2.35A,
respectively. The Cp and Phenyl rings are almost vertical in 1, but are almost coplanar in 2. In
˚
both compounds, the C–C bond distances in the Cp rings range between 1.407 and 1.431A.
˚
˚
=
The C O bond lengths in molecules 1 are 1.199A(3) for O(1)-C(6) and 1.206A(2) for O(3)-
C(11), in molecules 2 are 1.199A(5) for O(4)-C(11) and 1.203A(4) for O(1)-C(6). Additionaly,
the bond lengths are 1.467A(3) for C(5)-C(6) and 1.477A(3) for C(11)-C(12) in molecules
1, the bond lengths are 1.477A(3) for C(5)-C(6) and 1.479A(3) for C(11)-C(12) in molecules
˚
˚
˚
˚
˚
˚
˚
2 respectively, which are shorter than a normal C-C single bond lengths (1.53A) and longer

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
133
Figure . Asymmetric unit of the compound  and  with labelling and thermal ellipsoids at the % proba-
bility level.
˚
than a normal double bond lengths (1.32A).These structural features in complexes 1 and 2
=
indicate that there is partial delocalization of electrons from the ferrocene to C O groups. A
view of the crystal packing of 1 in the unit cell is shown in Fig. 2. The crystal packing of the
compound is stabilized by several non-bonded interactions. In an individual supramoecule,
the chains of 1 are connected to each other in an inversion dimmer via C–H···O interactions
˚
˚
(C(9)–H(9B)···O(4) = 2.477 A and C(8)–H(8A)···O(1) = 2.480 A) (Fig. 2a).These inversion
–
dimers are further connected by C H···C contacts (Fig. 2b). In the crystal packing of 2,
–
the molecules related by inversion are linked to each other via C H···O interactions (C(1)–
˚
˚
H(1)···O(1) = 2.694 A and C(8)–H(8B)···O(3) = 2.573 A) arranged into chains (Fig. 3a).
The bond angles around the central tetrahedra N, which are range from 110.89°(15) to
113.64°(15) for 1 and those are from 116.5°(3) to 121.8°(4) for 2. it is close to the value for
a regular tetrahedron. The C atoms in the Ph-rings deviate significantly from coplanarity,
the torsion angles of C-C-C-C are vary in the range [−0.9°(4)−1.0°(3) for 1 and −1.2°(7)-
1.1°(7)for 2]. also the torsion angles of C-C-C-C in two Cp rings are vary in the range
[−0.5°(2)−0.4°(2)for 1 and −0.9°(5)- 0.9°(5) for 2], What’s more, the methyl on the Phenyl-
rings are in a trans disposition to Cp in 1 and 2, These data show that both the size and the
tilt angle of Cp lessen after cyclization. In the molecule, the corresponding bonds also are
different on the two bridges, such as C-O, C-C and C-N bonds, we choose the right angles
to analyze the complex 1both the two Cp rings and the two bridges are almost overlapping,
but this phenomenon cannot occur to the complex 2. those difference maybe caused by the
different steric and stack interactions.
–
–
–
The intermolecular short contact C H···O, C H···π and C H···C stacking interactions
play significant roles in forming the 3-D structures. the whole molecular form a “foldered”
scoop structure 1 and a dragonfly structure 2 (Fig. 4). This kind of conformation is crucial to
its photochromic and photoinduced properties

134
X. LIU ET AL.
=
Figure . Crystal structure description of . The carbonyl C O oxygen of the ester group is involved in short
–
contact with CH via a C H···O interaction that leads to the formation of a one-dimensional (D) short con-
–
tacted network (Fig. a). Such D networks are further self-assembled via C H···π(Ph) interactions and form
–
a D sheet and D short contacted sheets via C H···C. (Fig. b).

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
135
=
Figure . Crystal structure description of : The carbonyl C O oxygen of the ester group is involved in short
–
contact with CH via a C H···O interaction that leads to the formation of a D network (Fig. a). Such D
–
networks are further self-assembled via C H···π interactions (Fig b). D short contacted network formed
–
by the C H···C short contact interaction (Fig c).
Photophysical properties of compounds
The absorption and fluorescence spectra of the two compounds in dichloromethane (CH2Cl2)
solutions at room temperature are shown in Fig. 5 and Fig. 6. we can see that the absorption
spectra exhibit two peak at about 228 nm and 257 nm, it is obvious the higher peak of the
complex 1 generally red shifts compare with 2, and the different could be caused by the twisted
intramolecular charge transfer (TICT) .Taking into account the excellent photoluminescent
properties of d6 coordination polymers, the photoluminescent properties of complexes 1 and
2 were studied in dichloromethane (CH2Cl2) at room temperature. As depicted in Fig. 5.
and Fig. 6. while both 1 and 2 exhibit an intense broad emission at at 334 nm and 395 nm
(λex = 257 nm), which is quite similar. Therefore, the origin of emissions of complexes 1 and

136
X. LIU ET AL.
Figure . Assembling of the molecules of  into a “foldered” scoop and  into a lot of “ dragonfly ” three-
dimensional structure (D).

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
137
Figure . The UV-vis spectroscopic measurements studies of compounds  and  in CHCl ( × − mol/L).
Figure . The fluorescence properties studies of compounds  and  in CHCl (−mol/L).

138
X. LIU ET AL.
Figure . IR spectra of  and .
2 may be attributed to the internal charge transfer (π→π∗ transitions) and the absorption
is attributed to π-π∗ transition of the whole π-conjugated system. The observation indicates
that their potential applications as enzyme models and molecular recognition hosts.
The infrared spectra of the two complexes were recorded in the range of 4000∼400 cm−1
=
with KBr pallets, as shown in Fig. 7. The C O absorption peak of carboxyl groups at
1719 cm−1 for 1 and 1723 cm−1 for 2 which means the formation of carboxylates. At the same
time, other different absorption peaks at 1626 cm−1 are observed in 2, should be ascribed

Figure . H NMR spectrum of  and  in CDCl.

MOLECULAR CRYSTALS AND LIQUID CRYSTALS
139
to the asymmetrical stretching vibration of -COO- groups. but it is not observed in 1, The
changes of IR spectra indicate different intramolecular contact in the two complexes. In order
to verify the structure change, we investigate the 1H NMR spectral changes of 3-CH3 and 2-
CH3 forms. The 1H NMR analysis of compound 1 in CDCl3 exhibited the signal changes of
protons in Fig. 8. For instance, the phenyl proton of compound 1 appeared as a singlet at δ:
7.17 and 6.63. However, the phenyl proton of compound 2 exhibited a singlet signals at д:7.26
and 7.09, respectively. The methyl resonance of compound 1 is observed at д: 2.34, and those
of the compound 2 appeared at д: 2.50, which may be attributed to the steric effect on the
methyl resonance in the different position.
Conclusion
In this study, two new ferrocenophane compounds were synthesized and mainly characterized
by 1H-NMR and X-ray diffraction. The molecular structures and packing diagrams of the title
compounds showed that the molecules form dimers and various ring motifs as part of the
chains stabilized by several non-bonded interactions. As expected, complexes 1 and 2 show
different photophysical properties. The title compounds have a potential of new chemical
sensors.
Funding
This work was supported by Instrumental Analysis Center of the Chemical engineering institute, the
Yu-Lin University, the Scientific research fund Project (grant nos. 2016NY-221) and Scientific research
plan projects of education department of shaanxi provincial government (grant nos. 15JK1849).
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