научная статья по теме 1D HELICAL OR LADDER MN(II) SUPRAMOLECULAR ISOMERISM BASED ON IMIDAZO-[4,5-F]-1,10-PHENANTHROLINE LIGAND Химия

КООРДИНАЦИОННАЯ ХИМИЯ, 2015, том 41, № 4, с. 228-233

УДК 541.49

1D HELICAL OR LADDER Mn(II) SUPRAMOLECULAR ISOMERISM BASED ON IMIDAZO-[4,5-f]-1,10-PHENANTHROLINE LIGAND

© 2015 Y. Ren*, M. An, M. Zhang, J. Wàng, L. Gao, and F. Fu

College of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Chemical Reaction Engineering,

Yan'an University, Yan'an, 716000P.R. China *E-mail: renyixia1@163.com Received August 9, 2014

Two isomeric Mn(II) complexes, [Mn(IDP)SO4 ■ 2H2O]n (I) and {[Mn(IDP)SO4 ■ H2O] ■ H2O}n (II), have been prepared by solvo-thermal reactions of imidazo-[4,5-f]-1,10-phenanthroline (IDP) ligand with manganese sulfate. The crystal structures of IDP, complexes I and II are characterized by single-crystal X-ray diffusion analyses (CIF files CCDC nos. 988128 (IDP), 988129 (I), and 988130 (II)). The structural analyses show that there are H-bonds and п—п stacking interactions resulting in the 3D supramolecular structure for IDP. Complex I exhibits 1D chain-like structure featuring the left- and right-handed helical chains, while in II, the 1D structure is a ladder-like structure. The п—п stacking interactions take an important role in the formation of supramolecule structures for complexes HL, I, II due to the large conjugated system of IDP ligand. The IR and UV-Vis absorption spectra of complexes I and II exhibit the difference, but the liquid-state photoluminescence of I and II is similar attributing to the intraligand п—п* transition.

DOI: 10.7868/S0132344X15040052

INTRODUCTION

The structural uncertainty of metal-organic coordination polymers increases the construction challenge of crystal engineering due to many factors such as metal coordination polyhedron, organic ligands, counter anions, solvent, and experimental conditions [1—3]. Supramolecular isomerism is a common phenomenon in the construction of coordination polymers, and it can be divided into two situations: (a) the metal centre ions are different but the structure is similar; (b) the base chemical compositions are the same but the networks are different [4—7]. Lots of supramolecular isomerism have been researched and reported not only for their structural diversity, but for the differences of their potential properties [8—11]. The induced reasons for the formation of the supramolecular isomerism are complex and the mechanism is still vague, in which the guest-induced, solvent-induced and reaction temperature-induced supra-molecular isomerisms are general [12—14], however, the additive-induced ones are several examples [15].

In this paper, we selected imidazo-[4,5-f]-1,10-phenanthroline (IDP) with the big conjugated system as an organic ligand to construct coordination polymers with Mn(II) salts in solvothermal conditions, and obtained a pair of supramolecular isomerisms with different structures - [Mn(IDP)SO4 ■ 2H2O]„ (I) and {[Mn(IDP)SO4 ■ H2O] ■ H2O}„ (II). Experiment analysis discovered that it was induced by an additive carboxyl organic ligand. Their crystal structures, IR,

UV and FS spectrum have been determined and discussed.

EXPERIMENTAL

Materials and methods. All chemicals were commercially available and used as received without further purification. Elemental analyses (CHN) were performed using an Vario EL elemental analyzer. FT-IR spectra were recorded from KBr pellets in the range of 4000-400 cm-1 on a Nicolet Avatar 360 FT-IR spectrometer. UV-Vis absorption experiments were performed on a SHIMADZU UV 2500PC spectrometer equipped with an integrating sphere for diffuse-reflectance spectroscopy, and the spectra were collected in the 200-800 nm range at room temperature. Fluorescence measurements were carried out with a F-4500 spectrofluorophotometer.

Recrystallization of IDP. The ligand was purchased commercially and recrystallized in water by hydrothermal method at 180°C for 72 h. The yellow prismlike crystals of IDP were collected by filtration, washed with ethanol and dried in air.

For C13H8N4 anal. calcd., %: Found, %:

C, 70.90; C, 71.12;

H, 3.66; H, 3.78;

N, 25.44. N, 25.62.

IR data for IDP (KBr; v, cm-1): 3447 m, 3103 w, 2363 m, 2344 m, 1606 m, 1566 m, 1409 w, 1064 m, 932 m, 802 m, 738 m.

>A M ' ^

fl

Fig. 1. 1D H-bonds chain along x axis of compound IDP.

Synthesis of I. A mixture of MnSO4 ■ H2O (0.018 g, 0.1 mmol) and IDP (0.032 g, 0.1 mmol) in the mixed solvent of 1 mL H2O and 1 mL isopropanol was stirred for 15 min, then added Na2Hstp (0.013 g, 0.1 mmol), and placed in a 23-mL Teflon-lined autoclave and heated at 140°C for 96 h. The autoclave was cooled over a period of 10 h by natural cooling. The straw yellow lath-like crystals of I were collected by filtration, washed with ethanol, and dried in air (the yield was 10 mg, ~21% based on Mn).

For C13H12N4O6SMn

anal. calcd., %: C, 38.34; H, 2.97; N, 13.76. Found, %: C, 38.65; H, 2.88; N, 13.54.

IR data for I (KBr; v, cm-1): 3445 m, 3103 w, 2365 m, 2337 m, 1607 m, 1559 m, 1419 w, 1117 m, 1067 m, 971 w, 940 m, 803 m, 731 m.

Synthesis of II. A mixture of MnSO4 ■ H2O (0.018 g, 0.1 mmol) and IDP (0.032 g, 0.1 mmol) in the mixed solvent of 1 mL H2O and 1 mL ethanol was stirred for 15 min, then placed in a 23-mL Teflon-lined autoclave and heated at 140°C for 96 h. The autoclave was cooled over a period of 10 h by natural cooling. The straw yellow lath-like crystals of II were collected by filtration, washed with ethanol, and dried in air (the yield was 10 mg, ~21% based on Mn).

For C13H12N4O6SMn

anal. calcd., %: Found, %:

C, 38.34; C, 38.59;

H, 2.97; H, 2.65;

N, 13.76. N, 13.66.

IR data for II (KBr; v, cm-1): 3442 m, 3103 w, 2364 m, 2343 m, 1608 m, 1559 m, 1421 w, 1130 m, 1084 m, 1069 m, 988 w, 971w, 941 m, 809 m, 734 m.

X-ray structure determination. Single crystal X-ray diffraction analysis of compounds IDP, I, II were carried out on a Bruker SMART APEX CCD diffractome-ter equipped with a graphite monochromated Mo^a radiation (X = 0.71073 Â). Raw data were integrated with the SAINT program [16]. The structures were solved by direct methods with SHELXS-97 and refined by full-matrix least-squares on F2 using SHELXS-97 [17]. An em-

pirical absorption correction was applied with the program SADABS [18]. All non-hydrogen atoms were refined anisotropically. The hydrogen atoms were set in calculated positions and refined by a riding mode. The crystallographic details of compounds IDP, I, II are provided in Table 1, and the selected bond distances and angles are listed in Table 2.

Supplementary material has been deposited with the Cambridge Crystallographic Data Centre (CCDC nos. 988128 (IDP), 988129 (I), and 988130 (II); depos-it@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).

RESULTS AND DISCUSSION

In IDP ligand, the hydrogen bonds of N—H---N join the IDP molecules into one-dimension chains along x axis as shown in Fig. 1 (in N(3)—H(3A)---N(1), N—N 3.007 A). The dihedral angel between two adjacent IDP molecules is 49.41°, which results the 1D chain into an undulating chain. Such 1D chains come into being 2D layer-structure in xy plane by n—n packing interactions (the distance of two adjacent IDP molecules is 3.578 A) between IDP molecules with the big n-conjugated system (Fig. 2). Furthermore, these 2D layers stack into 3D supramolecular structure in ••• ABAB ••• order along z axis.

Single-crystal X-ray diffusion analysis indicates that compound I exhibits a one-dimensional double-helical chain-like structure. As shown in Fig. 3a, the Mn(1) ion is hexa-coordinated by two nitrogen atoms (N(1) and N(2)) from IDP ligand, two oxygen atoms

(O(3) and O(4^)) from two SO4 anions, and two oxygen atoms (O(1) and O(2)) from two coordinated water molecules. The center metal Mn(1) ion lies in a distorted slightly octahedral geometry, for which O(1) and O(4^) atoms are two vertexes and N(1), N(2), O(2), and O(3) consist of the equatorial plane of octahedron as shown in Fig. 3a. The Mn—N bond lengths are 2.253(1) and 2.277(2) A, and Mn—O bonds range from 2.143(1) to 2.202(1) A. The adjacent metal ions

bridged by ^2-fashion SO4 anions into 1D chain-like structure and the IDP ligands hang vertically on the sides of the chain (Fig. 4). These chains are left- and right-handed helical chains based on the metal ions

KOOP,3HHAUHOHHAH XHMH3 tom 41 № 4 2015

Table 1. Crystal data and structure refinement for compounds IDC,

I, II

Parameter Value

IDP I II

M 220.23 407.27 407.27

T, K 295(2) 296(2) 296(2)

Crystal system Orthorhombic Monoclinic Monoclinic

Space group Pbca P2\/c P21/c

a, A 14.570(4) 10.935(2) 10.1690(10)

b, A 7.872(2) 7.0319(14) 6.5816(6)

c, A 16.980(4) 19.761(4) 11.7392(11)

P, deg 90 99.459(2) 112.654(10)

V, A3 1947.5(9) 1498.8(5) 725.07(12)

Z 8 4 2

Pcalcd, g cm-1 1.502 1.805 1.870

p., mm-1 0.096 1.063 1.099

9 Range, deg 2.40-27.57 2.58-28.35 1.88-28.30

Reflection collected/unique 10572/2239 8926/3644 4521/1908

Reflections with I > 2a(I) 1282 3232 1465

Rint 0.0645 0.0197 0.0257

Parameters refined 154 240 162

GOOF 1.021 1.034 1.049

R (I > 2ct(I))* 0.0472 0.0284 0.0381

wR2 (all data) 0.1097 0.0741 0.0870

Largest diff. peak/hole, e A-3 0.270/-0.207 0.495/ -0.362 0.423/-0.640

* R 1 = ВД - M; wR2 = [2w(Zo2 - Fc2)2/Ew(F2)2]1/2.

Table 2. Selected bond lengths for compounds IDP, I and II*

Bond d, A Bond d, A Bond d, A

IDP I II

C(1)-N(1) 1.325(3) Mn(1)-O(4)#1 2.1429(1) Mn(1)-O(7)#2 2.139(2)

C(5)-N(2) 1.387(2) Mn(1)-O(3) 2.1613(1) Mn(1)-O(7)#3 2.139(2)

C(6)-N(2) 1.318(3) Mn(1)-O(1) 2.1972(1) Mn(1)-O(6) 2.148(3)

C(6)-N(3) 1.357(3) Mn(1)-O(2) 2.2017(14) Mn(1)-O(9) 2.230(4)

C(7)-N(3) 1.375(2) Mn(1)-N(1) 2.2531(1) Mn(1)-N(3) 2.275(3)

C(11)-N(4) 1.324(2) Mn(1)-N(2) 2.2768(1) Mn(1)-N(4) 2.295(3)

* Symmetry codes: #1 1 - x, 0.5 + y, 0.5 - z; #2 1 - x, -y, 1 - z; #3

1 - x, 0.5 + y, 1 - z. КООРДИНАЦИОННАЯ ХИМИЯ том 41 № 4 2015

(a) (b)

Fig. 2. 2D layer-like structure by n—n packing interactions base on 1D H-bonds chains (a) and 3D supramolecular structure base on 2D layer in •••ABAB-- order along z axis (b) in compound IDP.

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