基于PbBr2的有機-無機雜化化合物的合成和晶體結構

袁國軍 劉光祥 劉少賢 馬 蕓

（南京曉莊學院環(huán)境科學學院，南京 211171）

基于PbBr2的有機-無機雜化化合物的合成和晶體結構

袁國軍＊劉光祥 劉少賢 馬 蕓

（南京曉莊學院環(huán)境科學學院，南京 211171）

合成得到了 2 個新的有機-無機雜化化合物 {（4-CH3-Bz-4-Ph-Py）[PbBr3]}n（1）（4-CH3-Bz-4-Ph-Py+=4-甲基芐基-4-苯基吡啶離子）和{（4-F-Bz-4-Ph-Py）[PbBr3]}n（2）（4-F-Bz-4-Ph-Py+=4-氟芐基-4-苯基吡啶離子）。 對化合物 1 和 2 進行了元素分析、粉末 X 射線衍射等表征,并利用X射線單晶衍射測定了它們的單晶結構,配合物1與2同構,均屬于正交晶系,P21212空間群。結構研究表明,配合物1和2中,鉛溴八面體通過共邊連接方式,形成[Pb3Br9]n三鏈,有機陽離子填充在無機溴化鉛鏈空隙中。配合物1和2均未作手性分離。

溴化鉛；有機-無機雜化化合物；晶體結構

In the context of haloplumbate-based hybrids，the perovskite-type ones have attracted tremendous research interest. The 3D haloplumbate-basedperovskites，（CH3NH3）PbI3-xClx，with much lower exciton binding energies and intense light absorption over the whole visible light region have been employed as absorbers in solar cells.It is remarkable that the records of certified power conversion efficiencies have being constantly updated and over merely a few years，the power conversion efficiency has been enhanced to 22.1%[20].Most recently，the （CH3NH3）PbI3-xClxperovskites have been found to show amazing bipolar and bistable resistive switching behavior with small on-off voltage （＜1.0 V）in a simple metal-dielectric-metal capacitor configuration device memory field[23].The 2D haloplumbate-based hybrids，（N-MEDA）[PbBr4-xClx]（N-MEDA=N-1-methylethane-1，2-diammonium，x=0 ～1.2），are single-phase white-light emitters，and their broadband emission across the entire visible spectrum arises from corrugated lead halide sheets.Interestingly，the emission is tunable through halide substitution to afford both “warm”and “cold” white light in such haloplumbate-based wide-band gap semiconductors[14].The 1D iodoplumbate-based hybrids were reported to display ferroelectricity，wherein the polarization is switchable under an alternating current electrical field[24].

In addition， a 3D open-framework hybrid，{（EDAMP）2[Pb7I18]·4H2O}n（EDAMP2+=Et2NHC6H4-CH2C6H4NHEt2），in which the inorganic framework is built from purely octahedral PbI6units and behaves as a quantum-wire array，shows a fascinating wavelengthdependent photochromic behavior[25].Its color changes from yellow to olive green under illumination by light with λ=500 nm and further to dark green by light with λ ＜500 nm.Most interestingly，the reversion of the color for the hybrid can be accomplished by heating，indicating that this hybrid possesses switchable photochromic nature.It is well known that a materialwith switchable functionality through external stimuli，such as thermally-triggered，irradiation-induced and applied pressure，isvery useful for application in the fields of sensors，memory and data storage[26-29].

In this study，we report the syntheses and crystal structures of two haloplumbate-based hybrids，{（4-CH3-Bz-4-Ph-Py）[PbBr3]}n（1）and {（4-F-Bz-4-Ph-Py）[PbBr3]}n（2）.

1 Experimental

1.1 Materials and general methods

All chemicals and solvents were reagent grade and used without further purification.（4-CH3-Bz-4-Ph-Py）Brand （4-F-Bz-4-Ph-Py）Brwere synthesized according to a similar procedure described in the literature[30].Elemental analyses for C，H and N were performed with an Elementar Vario ELⅢanalytic instrument.Powder X-ray diffraction （PXRD）data for 1 and 2 were collected on a Rigaku/max-2550 diffractometer with Cu Kα radiation （λ=0.154 18 nm）at room temperature.The acceleration voltage was 40 kV with a 40 mA current flux.The data were collected in the 2θ range from 5°to 50°.

1.2 Synthesis of{(4-CH3-Bz-4-Ph-Py)[PbBr3]}n(1)

A mixture of （4-CH3-Bz-4-Ph-Py）Br，KBr and PbBr2with a molar ratio of 1∶1∶1 in DMF （25 mL）was placed in an oven and slowly evaporated at 55℃for 10～14 days to produce light yellow needle-shaped crystals in ca.95%yield.Elemental analysis calculated for C38H36N2Pb3Br8（%）：C 25.62，H 2.04，N 1.57;Found（%）：C 25.60，H 2.03，N 1.55.

1.3 Synthesis of{(4-F-Bz-4-Ph-Py)[PbBr3]}n(2)

The synthesis of 2 was the same as that of 1 except that （4-F-Bz-4-Ph-Py）Br was used instead of（4-CH3-Bz-4-Ph-Py）Br.Yellow needle-shaped crystals were gained in ca.95%yield.Elemental analysis calculated for C36H30N2Pb3Br8F2（%）：C 24.16，H 1.69，N 1.57;Found（%）：C 24.11，H 1.65，N 1.54.

1.4 X-ray crystallography

Two block single crystals of 1 and 2 with dimensionsofboth0.19mm ×0.18mm ×0.17mm were selected under an optical microscope and glued to thin glass fibers，respectively.X-ray diffraction intensity data were collected on a Bruker APEXⅡCCD diffractometer equipped with a graphite monochromated Mo Kα （λ=0.071 073 nm）using the φ-ω scan mode at 296（2）K.Data reductions and absorption corrections were performed with the SAINT and SADABS software packages[31]，respectively.Structures were solved by direct methods and refined by full matrix leastsquares with SHELXL-2014/7 software package[32].The non-hydrogen atoms were anisotropically refined using the full-matrix least-squares method on F2.All hydrogen atoms were placed at the calculated positions and refined riding on the parent atoms.The details about data collection，structure refinement and crystallography are summarized in Table 1.

CCDC：1572941，1;1572942，2.

Table 1 Crystallographic and structure refinement data for 1 and 2

2 Results and discussion

2.1 Description of crystal structure

Compound 1 crystallizes in the P21212 space group at room temperature and no chiral separation was done.The asymmetric unit，as shown in Fig.1，consists of one Pb2+ion and three different Br-anions together with one 4-CH3-Bz-4-Ph-Py+cation.The Pb2+ion is located at an inversion center and coordinated with six Br-to form the slightly distorted PbI6octahedron.The Pb-Br lengths range from 0.271 38（23）to 0.349 15（20）nm and the Br-Pb-Br angles fall within the range of 83.754（46）°～172.861（50）°at 296 K，these geometry parameters within the coordination octahedron are comparable to other haloplumbates.Three different Br-ions are adopted in the μ3-bridged model to connect three neighboring Pb2+ions.The adjacent PbBr6coordination octahedral are connected together via the edge-sharing mode to form a uniform[Pb3Br9]nchain along the a-axis direction （Fig.2）.

Fig.1 ORTEP view of 1 with thermal ellipsoids at 30%probability level

Fig.2 Edge-sharing octahedral chain of[Pb3Br9]nin compounds 1 and 2

The cation is composed of a 4-phenylpyridine and a 4-methylbenzyl，and the neighboring cations are aligned into quadrilateral-shaped 1D channels，and the inorganic [Pb3Br9]nchains reside in the channels（Fig.3）. Charged-assisted H-bonding interactions appear between the CH2groups in the cations and the Br-ions in the inorganic chains.Compound 2 （Fig.4～5）is isostructural with compound 1.

Fig.3 Molecular packing diagram for compound 1

Fig.4 ORTEP view of 2 with thermal ellipsoids at 30%probability level

Fig.5 Molecular packing diagram for compound 2

2.2 Powder X-ray diffraction(PXRD)

PowderX-ray diffraction （PXRD） analyses were carried out for 1 and 2 at room temperature to characterize their purity.As shown in Fig.6，the measured peak positionsclosely match the simulated peak positions，indicative of pure products.

Fig.6 PXRD patterns of compounds 1 （a）and 2 （b）

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Syntheses and Crystal Structures of Two Homogeneous Organic-Inorganic Compounds Based on PbBr2

YUAN Guo-Jun＊LIU Guang-Xiang LIU Shao-Xian MA Yun
（School of Environmental Science,Nanjing XiaoZhuang University,Nanjing 211171,China）

Two homogeneous compounds，{（4-CH3-Bz-4-Ph-Py）[PbBr3]}n（1）（4-CH3-Bz-4-Ph-Py+=4-methylbenzyl-4-phenylpyridinium）and{（4-F-Bz-4-Ph-Py）[PbBr3]}n（2）（4-F-Bz-4-Ph-Py+=4-fluorobenzyl-4-phenylpyridinium），have been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction.Compounds 1 and 2 are isostructural，and crystallize in orthorhombic，space group P21212.Structure analyses reveals that haloplumbate ion exhibits octahedron topology in compounds 1 and 2，and all these octahedron topologies formed 1D polymeric chain through edge-sharing connecting modes.The flack values of 1 and 2 are 0.340（13）and 0.453（10），respectively.No chiral separation was done for both compounds.CCDC：1572941，1;1572942，2.

lead bromide;organic-inorganic hybrid compounds;crystal structure

0 Introduction

considerable research interests due to their tunable structures from the discrete mononuclear or polynuclear species （zero-dimensional;abbr.0D）to the infinite variety with higher dimensionality[1-13]（onedimensional[1，3-9]，two-dimensional[10-11]or three-dimensional[2];hereafter abbr.as 1D，2D and 3D，respectively）and the wide range of novel physical properties，beneficial in optics[14-20]and electronics[21-22].

O614.43+3

A

1001-4861（2018）02-0404-05

10.11862/CJIC.2018.055

2017-09-10。收修改稿日期：2017-12-05。

江蘇省自然科學基金（No.BK20170145）、江蘇省教育廳高校自然科學研究面上項目（No.15KJB150019）和江蘇省高等學校大學生實踐創(chuàng)新訓練計劃（No.201711460016X）資助。

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