научная статья по теме HYDROTHERMAL SYNTHESIS, CRYSTAL STRUCTURE, AND PHOTOLUMINESCENCE OF PB(II) AND MN(II) COORDINATION POLYMERS BASED ON IMIDAZO[4,5-F][1,10]PHENANTHROLINE Химия

КООРДИНАЦИОННАЯ ХИМИЯ, 2013, том 39, № 6, с. 356-360

УДК 541.49

HYDROTHERMAL SYNTHESIS, CRYSTAL STRUCTURE, AND PHOTOLUMINESCENCE OF Pb(II) AND Mn(II) COORDINATION POLYMERS BASED ON IMIDAZO[4,5-f][1,10]PHENANTHROLINE

© 2013 K. Cheng1 and X. L. Zhang2, *

1School of Chemistry and Pharmaceutical Engineering, Shandong Polytechnic University, Jinan, 250353 P.R. China 2Key Laboratory of Coordination Chemistry and Functional Materials in Universities of Shandong, Dezhou University,

Dezhou, 253023 P.R. China *E-mail: xlzhang99@126.com Received October 11, 2011

Two new coordination polymers, [Pb(IDPT)2(NO3)2] (I) and [Mn(IDPT)(SO4)(H2O)2] (II) (IDPT = imi-dazo[4,5-f][1,10]phenanthroline), were synthesized by hydrothermal method and characterized by elemental analysis and single-crystal X-ray diffraction technique. The results reveal that the complex I belongs to monoclinic crystal system, space group C2/c and complex II belongs to monoclinic crystal system, P2x/c space group. The cell parameters are: a = 19.1970(13), b = 7.3875(5), c = 17.3825(12) A, в = 100.47(10)°, V = 2424.0(3) A3, Z = 4, F(000) = 1488 for I; a = 10.9135(6), b = 7.0230(4), c = 19.7034(10) A, в = = 99.32(10)°, V = 1490.25(14) A3, Z = 4, F(000) = 828 for II. In the structure of complex I, the metal center Pb(II) is six-coordinated, displays an octahedral geometry. Each molecule is further connected with neighboring one via n—n interactions into 1D chain. In complex II, Mn(II) is six-coordinated to form a distorted octahedral geometry. Compound II displays 1D supramolecular chain formed through hydrogen bonds. Additionally, the fluorescent properties for the complexes were investigated. Complexes I and II exhibit strong photoluminescence with emission maximum at 583 and 529 nm at room temperature.

DOI: 10.7868/S0132344X13060029

INTRODUCTION

The design and synthesis of coordination polymers have been increasing over the past decade owing to their diverse topologies and potential applications in the area of magnetism, porosity and luminescence [1—7]. At present, many metal-organic complexes with novel structure and good properties were successfully prepared through molecular self-assembly [8]. The critical issue is the rational choice of metal ions and organic ligands during the self-assembly process. Usually, the complexes were prepared through the assembly of transition metal ions with nitrogen-containing ligands, such as phenanthroline, imidazole and pyridine. We choose the imidazo [4,5-f][ 1,10] phenanthroline (IDPT) as the major ligand to design and synthesized new coordination polymers. Two new complexes were obtained and they were characterized by elemental analysis and single crystal X-ray diffraction method. And the properties offluorescence were also investigated.

EXPERIMENTAL

Materials and instruments. All reagents and solvents for the synthesis and analysis were commercially available and used as received. Elemental analysis was

performed on a PerkinElmer 240 C element analyzer. Crystal structure was collected on Bruker SMART APEX II CCD single crystal diffractometer. Solidstate uorescence spectra were recorded at room temperature with an F-4500 equipped with a xenon lamp and a quartz carrier.

Synthesis of [Pb(IDPT)2(NO3)2] (I). A mixture of Pb(NO3)2 (132 mg, 0.4 mmol), IDPT (88 mg, 0.4 mmol), 2,5-dimercapto-1,3,4-thiadiazole (DMTD) (60 mg, 0.4 mmol), NaOH (16 mg, 0.4 mmol), and distilled water (10 mL) was sealed in a 25 mL teflon-lined stainless steel vessel and heated to 150°C for 48 h. After cooling to room temperature in 24 h, the products were orange crystals that were washed with distilled water to give pure samples (the yield was 30% based on Pb(II)).

For C26H16N10O6Pb

anal. calcd., %: C, 40.43; H, 2.07; N, 18.14. Found, %: C, 40.03; H, 1.93; N, 17.58.

Synthesis of [Mn(IDPT)(SO4)(H2O)2] (II). A mixture of MnCl2 • 6H2O (39.6 mg, 0.2 mmol), IDPT (88 mg, 0.4 mmol), DMTD (60 mg, 0.4 mmol), NaOH (16 mg, 0.4 mmol), and distilled water (10 mL) was sealed in a 25 mL teflon-lined stainless steel vessel and heated to 150°C for 48 h. After cooling to room

temperature in 24 h, the orange crystals were obtained (the yield was 36% based on Mn(II)).

Table 1. Crystallographic data and structure refinement summary for I and II

For C13H12N4O6SMn

anal. calcd., %: Found, %:

C, 38.30; C, 37.89;

H, 2.95; H, 2.66;

N, 13.75. N, 13.04.

X-ray structure determination. Diffraction intensity data of single crystals of the complex was collected on a Bruker SMART APEX II CCD diffractometer equipped with a graphite monochromatic Mo^a radiation (X = 0.71073 Â) by using a «-scan mode. An empirical absorption correction was applied using the SADABS programs [9]. The structures was solved by direct methods and rened by full-matrix least-squares methods on F2 using the program SHEXL-97 [10, 11]. All non-hydrogen atoms were rened by Fourier syntheses. The hydrogen atoms bonded to carbon were located by geometrical calculations and their positions and thermal parameters were xed during the structure renement. The crystallographic data, experimental details and structural analyses of the metal complexes was summarized in Table 1. Selected bond and angle parameters are listed in Table 2. Hydrogen bonds of complex II are listed in Table 3.

Crystallographic data for two complexes have been deposited with the Cambridge Crystallographic Data Centre (nos. 834627 (I) and 814229 (II); deposit@ccdc. cam.ac.uk or http://www.ccdc.cam.ac.uk).

RESULTS AND DISCUSSION

Two new coordination polymers I and II were obtained when we used IDPT and DMTD as mixed ligands to react with Pb2+ or Mn2+ cations under hydrothermal conditions. From the results of single crystal X-ray diffraction analysis we can know that the DMTD ligand was not involved in complex I and in complex II sulfate anion was found to coordinate to the Mn2+ cation. This might be attributed to the DMTD decomposing into sulfate anion with the catalysis of manganese ions.

The fundamental unit for complex I is shown in Fig. 1. Each Pb2+ ion is coordinated by four N-atoms from two same IDPT ligands and two oxygen atoms from two same nitrates in a distorted octahedral coordination geometry. The bond lengths Pb(1)—N range from 2.535(3) to 2.607(3) A, and the bond lengths for Pb(1)—O is 2.875(3) A. The bond angles between the donor atoms around the Pb(II) center range from 64.16(9)° to 144.10(9)°. In the crystal structure, the centroid distances between eighboring parallel IDPT ligands of the neighboring chains are 3.4683, 3.5159, and 3.6522 A, which reveals that there exist n—n stacking interactions between adjacent IDPT ligands. Hence, the 1D supramolecular chain of complex I was formed via n—n stacking interactions, as shown in Fig. 2.

Value

Parameter

I II

Formula weight 771.68 407.27

Crystal system Monoclinic Monoclinic

Space group C2/c P2 x/c

Unit cell dimensions:

a, A 19.1970(13) 10.9135(6)

b, A 7.3875(5) 7.0230(4)

c, A 17.3825(12) 19.7034(10)

ß, deg 100.47(10) 99.32(10)

V, A3 2424.0(3) 1490.25(14)

Z 4 4

Pcalcd mg m-3 2.114 1.815

/(000) 1488 828

9 Range, deg 2.16-25.00 1.89-24.99

Reflections collected/unique 6022/2138 7346/2614

Rint 0.0248 0.0200

Reflections with I > 2a(I) 2032 2334

Data/restraints/parameters 2138/18/227 2614/0/226

Goodness-of-fit on F 2 1.061 0.98

R1, wR2 (I > 2a(I)) 0.0189, 0.0503 0.0274, 0.0732

wR2 (all data) 0.0206, 0.0512 0.0315, 0.0750

Largest diff. peak and hole, e/A3 0.746 and -0.555 0.509 and -0.243

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358 CHENG, ZHANG

Table 2. Selected bond lengths and bond angles for I and II*

Bond d, Â Bond d, Â

Pb(1)-N(1) Pb(1)-N(2) Mn(1)-O(1)#2 Mn(1)-O(2) Mn(1)-O(2w) 2.535(3) 2.607(3) I 2.1394(16) 2.1590(15) 2.1923(16) Pb(1)-O(1) I Mn(1)-O(1w) Mn(1)-N(1) Mn(1)-N(2) 2.875(3) 2.1924(15) 2.2519(17) 2.2739(18)

Angle ro, deg Angle ro, deg

N(1)#!pb(1)N(1) N(1)#!pb(1)N(2) N(1)Pb(1)N(2) N(2)#!pb(1)N(2) O(1)#2Mn(1)O2 O(1)#2Mn(1)O(2w) O(2)Mn(1)O(2w) O(1)#2Mn(1)O(1w) O(2)Mn(1)O(1w) O(2w)Mn(1)O(1w) 90.09(13) 84.13(9) 64.16(9) 135.23(13) I 91.52(6) 174.65(6) 86.82(6 91.53(6) 97.65(6) 93.73(6) N(1)#xPb(1)O(1) N(1)Pb(1)O(1) N(2)#xPb(1)O(1) N(2)Pb(1)O(1) I O(1)#2Mn(1)N(1) O(2)Mn(1)N(1) O(2 w)Mn(1)N(1) O(1w)Mn(1)N(1) O(1)#2Mn(1)N(2) O(2)Mn(1)N(2) 144.10(9) 70.46(9) 83.54(9) 111.65(9) 88.71(6) 93.70(6) 86.33(7) 168.63(6) 96.27(6) 164.70(6)

* Symmetry transformations used to generate equivalent atoms: #1 -x + 1, y, - z + 1/2; #2 -x + 2, y - 1/2, — z + 1/2.

Table 3. Geometric parameters of hydrogen bonds for II*

Contact D H-A Distance, Â Angle DHA, deg

D-H H-A D-A

N(3)-H(3A)-O(4)#3 0.86 1.92 2.766(2) 167

O(1w)-H(12w)-O(2)#2 0.84 2.11 2.945(2) 174

O(1w)-H(11w)-O(3)#1 0.84 1.90 2.713(2) 160

O(2w)-H(21w)-N(4)#4 0.85 1.91 2.742(2) 168

O(2w)-H(22w)-O(3) 0.85 1.99 2.739(2) 147

* Symmetry transformations used to generate equivalent atoms: #1 —x + 2, y - 1/2, — z + 1/2; #2 —x + 2, y + 1/2, — z + 1/2; #3 —x + 1, y - 1/2, -z + 1/2; #4 -x + 1, -y + 2, -z.

In compound II, each independent Mn2+ cation is coordinated by two N atoms of IDPT ligands and four O atoms from two sulfate anions and two water molecules to furnish a distorted octahedral geometry, as shown in Fig. 3. The bond lengths Mn(1)—N(1) and Mn(1)—N(2) are 2.2519(17) and 2.2739(18) A. The bond lengths of Mn(1)-O(1), Mn(1)-O(2), Mn(1)-O(1w), Mn(1)—O(2w) are very close (2.1394(16), 2.11590(15), 2.1924(15), and 2.1923(16) A, respectively). There are strong hydrogen bonds in complex II as shown in Table 3. The distances of D---A range from 2.713(2) to 2.945(2) A. The angles of the D-H-A range from 147° to 174°. So 1D supramolecular chain of complex II is formed via hydrogen bonds (Fig. 4).

Metal-organic coordination polymers with transition metal have been investigated for their photo-

Fig. 1. Molecular structure of complex I. Hydrogen atoms have been omitted for clarity.

KOOP^HH^HOHHAtf XHMH3 tom 39 № 6 2013

Fig. 2. The 1D supramolecular chain through n—n interaction

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