Stereochemically active lone pair on lead(II) nano 3D supramolecular network: Synthesis,structural characterization,thermal stability and DFT calculation of [Pb(p-2-minh) 2 ]

Abstract

The novel nano lead(II) coordination compound [Pb(p-2-minh)₂] (1) (p-2-minh=pyridin-2-ylmethylene-isonicotinohydrazide) was synthesized by a sonochemical method. The new nano structure was characterized by using scanning electron microscopy (SEM), X-ray powder diffraction, elemental analysis, and thermal analysis. The single-crystal X-ray structure shows that the overall structure of 1 is a discrete coordination compound. This is further extended into a three-dimensional (3-D) supramolecular structure by π - π and other weak directional intermolecular interactions. The coordination number of the Pb(II) ions is six, PbN₄O₂. The PbO nanoparticles were obtained by the thermolysis of 1 at 180°C with oleic acid as a surfactant. The average diameter of the nanoparticles was estimated by the Scherrer equation to be 18 nm. The morphology and size of the prepared PbO samples were further observed using SEM.

Keywords

Nano coordination compound ultrasonic supramolecular interaction nano lead(II) oxide

1 Introduction

Supramolecular chemistry is defined by Jean-Marie Lehn as “...the chemistry of the intermolecular bond, covering the structures and functions of the entities by association of two or more species [1]. The design and synthesis of extended network materials has been an area of intense research over the past decade. Specifically, the porous nature of many of these materials makes them attractive for numerous applications [2 –11].

Discrete coordination compound (DCC) involves the synthesis of discrete, supramolecular entities that exist both in solution and the solid state [12]. One of the more prevalent and effective design strategies has been that of the directional-bonding approach [12]. In this building block-based methodology, complementary subunits are reacted in the appropriate ratio to give a final aggregate whose size and structure are dictated by the molecular information stored within the precursors themselves.The angles between the bonding sites of the subunits and the composition of the subunits preprogram the overall topology of the resultant product. Reactions of this sort occur in a single, high-yield step and often utilize readily-available building blocks. This process thus allows for a high degree of “synthetic economy” over more laborious covalent syntheses and has shown itself broadly applicable, in some cases even leading to self-assembled species that fall within the domain of small proteins in terms of molecular weight [2]. Additionally, due to the modularity of the approach, various functional groups can be incorporated into the design of any given assembly, further augmenting its versatility and the potential for future applications [13 –17].

Lead(II) frameworks have additionally attracted great interest because of lead’s large ion radius, a variable coordination number, and the possible occurrence of a stereochemically active lone pair of 6s² outer electrons as well as novel network topologies [18]. According to the hard-soft acid-base theory, the intermediate coordination ability of Pb(II) means that it can flexibly coordinate small nitrogen or oxygen atoms as well as large sulfur atoms [19]. The investigation of “stereo-chemical activity” of valence shell electron lone pairs in polymeric and supramolecular compounds may be more interested [20]. Lead(II) has an electronic structure [Xe]4f¹⁴5d¹⁰6s². Due to relativistic effects the 6s orbital is contracted and stabilized. As mentioned above, this stabilized 6s pair reduces its participation in the chemistry of the element (becoming an “inert-pair”) and this explains why inorganic Pb forms compounds in a lower oxidation state (less by two) than would be expected from its group number [21]. The apparent reticence of the 6s electrons to play a role in the chemistry of the element may also affect the stereochemistry of Pb(II) complexes. This influence can be understood in terms of simple hybridization or valence shell electron-pair repulsion arguments [22]. It seems that the 6s orbital, in spite of its stabilization, can hybridize with the 6p orbitals to give a “stereochemically active” 6s electron pair occupying one position in the coordination sphere of the metal. Because the pair is not directly detectable, its presence is normally identified by a void in the distribution of the coordination bonds (symmetrical coordination (hemidirected), see Scheme 1). If hybridization does not occur and the pair has only s character, then it is “stereochemically inactive” and the complex does not show a gap or void in the bond distribution (asymmetrical coordination (holodirected), see Scheme 1) [14].

As a continuation of the previous study [23 –31], in this paper we report the mew asymmetrical lead(II) coordination compound in the presence of 2-pyridinecarbaldehydebisonicotinoylhydrazone schiff-base ligand describe a simple synthetic sonochemical preparation of nano-structures of this coordination polymer and its use in the preparation of PbO nanoparticles.

2 Experimental

2.1 Materials and physical measurements

pyridin-2-ylmethylene-isonicotinohydrazide ligand (p-2-minh) was synthesized according to a literature method [33]. All other chemicals were obtained from Sigma-Aldrich (Seoul, South Korea) and were used as-received without further purification. A microanalyzer (Vario Microanalyzer) was used for C, H, and N elemental analyses of the samples. The IR spectra were performed on a spectrometer (Bruker Vector 22 FT-IR) by using KBr disks in the 4000 to 400 cm^–1 range. X-ray powder diffraction (XRD) measurements were performed using an X’pert diffractometer (Panalytical) with monochromatized Cu-k_α radiation. Simulated XRD powder patterns based on single crystal data were prepared using mercury [34]. The morphology of the samples was determined via scanning electron microscopy (SEM) (S-4200, Hitachi, Japan) and transmission electron microscopy (JEM-2200FS, JEOL Ltd., Japan).A multiwave ultrasonic generator (Sonicator_3000, Misonix Inc., Farmingdale, NY, USA), equipped with a converter/transducer and titanium oscillator (horn), 12.5 mm in diameter, operating at 20 kHz with a maximum power output of 600 W at room temperature for 1 h, was used for the ultrasonic irradiation. The chemical composition and evaluation of the chemical state of the product were performed by X-ray photoelectron spectroscopy (XPS) (K-ALPHA, U.K.).

2.2 Preparation of nano structure and single crystal of [Pb(p-2-minh)₂] (1)

To prepare the nano structure of [Pb(p-2-minh)₂] (1), 15 mL of a 0.1M solution of Pb(CH₃COO)₂·3H₂O in H₂O was positioned in a high density ultrasonic probe, operating at 20 kHz with a maximum power output of 600 W. Into this solution, 30 mL of a 0.1M solution of the ligand “p-2-minh” was added dropwise. The obtained precipitates were filtered off, washed with water, and then dried in air.

Product 1: m.p. = 130°C; yield: 68%. Analysis: Found; C: 44.00, H: 3.00, N: 17.00 %. Calculated for C₂₄H₁₈N₈O₂Pb: C: 43.83, H: 2.76, N: 17.04 %. FT-IR (selected bands, in cm^–1): 699 s, 761 m, 854 m, 1023 m, 1149 m,13509 s,1461 m, 1565 m, 1601 m, 2923 m [35].

To isolate single crystals of [Pb(p-2-minh)₂] (1), “p-2-minh” (0.46 g, 2 mmol) was placed in one arm of a branched tube [36], and Pb(CH₃COO)₂·3H₂O (0.38 g, 1 mmol) was placed in the other. Methanol was then carefully added to fill both arms, the tube was sealed, and the ligand-containing arm was immersed in a bath at 60°C. The other arm was left at ambient temperature. After two days, crystals (m.p. 133°C) suitable for an X-ray structure determination had deposited in the arm at ambient temperature. They were then filtered off, washed with acetone and ether, and air-dried (yield: 92%). Analysis: found C: 44.00, H: 3.00, N: 17.00 %. Calculated for C₂₄H₁₈N₈O₂Pb: C: 43.83, H: 2.76, N: 17.04 %. FT-IR (selected bands, in cm^–1): 699 s, 761 m, 854 m, 1023 m, 1149 m,13509 s,1461 m, 1565 m, 1601 m, 2923 m [35].

2.3 Synthesis of lead(II) oxide nanoparticles

The precursor of [Pb(p-2-minh)₂] (1) (0.2 mmol) was dissolved immediately in 5.00 mL of oleic acid, thus forming a light yellow solution. This solution was degassed for 45 min and then heated to 180°C for 2 h. At the end of the reaction, a black precipitate was formed. A small amount of toluene and a large excess of EtOH were added to the reaction solution, and PbO nanoparticles were separated by centrifugation. The solids were washed with EtOH and dried under air atmosphere (yield: 60%).

2.4 Crystallography

A crystal of the compound (yellow, Needle-shaped, size 0.01×0.22×0.30 mm) was mounted on a glass fiber with epoxy. Data collection was performed using an X-ray diffractometer (SMART APEX II, Bruker) with graphite-monochromated Mo K_α radiation (λ= 0.71073 Å), operating at 50 kV and 30 mA over 2θ ranges of 7.34 to 52.00°. No significant decay was observed during the datacollection.

Data were processed on a PC using the Bruker AXS Crystal Structure Analysis Package [37]. The following modules of the AXS package were used. Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); absorption correction: SADABS (Bruker, 2008); structure solution: XPREP (Bruker, 2008), and SHELXS-97 (Sheldrick, 2008); structure refinement: SHELXL-97 (Sheldrick, 2008); molecular graphics and publication materials: SHELXTL (Sheldrick, 2008). Neutral atom scattering factors were taken from Cromer and Waber [38]. The sample underwent phase transition at a low temperature. The data was thus collected at room temperature. The crystal is orthorhombic space group Pbcn, based on the systematic absences, E statistics, and successful refinement of the structure. The structure was solved by direct methods. Full-matrix least-square refinements minimizing the function Σw (F_o²–F_c²) ² were applied to the compound. All non-hydrogen atoms were refined anisotropically. All H atoms were placed in geometrically calculated positions, with C-H = 0.95 (aromatic), and 0.98(CH₃) Å, and refined as riding atoms, with Uiso(H) = 1.5UeqC(CH₃) or 1.2 UeqC(other C). Crystallographic data, bond lengths, and angles are given in Tables 2 and 3.

2.5 Computational details

The geometry of 1 has been optimized using the B3LYP density functional model [39, 40] and X-ray structure data. In these calculations the 3-21G* basis set was used for C and H atoms, while the 6-31G* basis set was used for N atoms. For the Pb atoms, the LanL2DZ valence and effective core potential functions were used [41, 42]. All DFT calculations were performed with the Gaussian 98 R-A.9 package [43].

3 Results and discussion

The reaction between the “p-2-minh” ligand with Pb(CH₃COO)₂·3H₂O led to the formation of the new lead(II) coordination compound [Pb(p-2-minh)₂] (1). Nano structures of 1 were obtained by ultrasonic irradiation in a methanolic solution, and single crystalline material was obtained using a heat gradient applied to a solution of the reagents (the branched tube method [36]). Scheme 2 gives an overview of the methods used for the synthesis of 1 using the two different routes.

The elemental analysis and IR spectrum of the nano-structure and the single crystalline material are indistinguishable. The selected spectral data and the corresponding data obtained from DFT calculations are given in Table 1. The FT-IR spectrum of the nano-structures and the single crystalline materials show the characteristic absorption bands of the “p-2-minh” ligand. The relatively weak band around 3064 cm^–1 is attributed to the absorption of the aromatic CH hydrogen atoms. The absorption band in the frequency range 1499–1634 cm^–1 correspond to aromatic rings vibrations of “p-2-minh” ligand. The absorption bands with strong intensity in the 1460 cm^–1 correspond to C = N of imine group of the “p-2-minh” ligands [35].

Figure 1(a) shows the XRD pattern of 1 simulated from single crystal X-ray data. The experimental XRD pattern of 1, prepared by using the sonochemical process, is shown in Fig. 1(b). Acceptable matches, with slight differences in 2Θ, were observed between the simulated and experimental powder X-ray diffraction patterns (Fig. 1(b)). This indicates that the compound obtained is a single crystalline phase and that this phase is identical to that obtained by the sonochemical approach. The obtained value is D = 28 nm, as estimated by using the Scherrer formula (D = 0.891λ/βcos Θ, where D is the average grain size, λ is the X-ray wavelength (0.15405 nm), and Θ and β are the diffraction angle and full-width at half-maximum of an observed peak, respectively).

Figure 2 shows the nano sheet structures that were observed by SEM. The mechanism of formation of these structures needs to be further investigated. However, it may be a result of the crystal structure of a compound that is a supramolecular structure; i.e., the packing of the structure on a molecular level might have influenced the morphology of the nano structure of the compound [23–31 , 44–47].

The X-ray structure of 1 revealed the composition and stereochemistry of a fundamental building block with a formula of [Pb(p-2-minh)₂]. A view of the molecular structure of 1, together with a selected atom numbering scheme, is shown in Fig. 3.

The lead(II) atom is coordinated by tow oxygen atoms of tow “p-2-minh” ligands with similar Pb–O distances of 2.359 (2) Å, and four nitrogen atoms of tow “p-2-minh” with similar Pb–N distances of 2.552 (3) and 2.552 (2) Å in a three-fashion with a PbN₄O₂ donor set. Thus, the coordination number of the lead(II) atom is six. Massive asymmetry can be seen in the coordination sphere of the Pb centers.

This arrangement suggests a hole in the coordination geometry around the metal ions that is occupied possibly by a “stereo-active” lone pair of electrons on lead(II) [48]. The observed shortening of the Pb–O bonds on the side of the Pb^2 + ion opposite to the putative lone pair (2.359 (2) Å compared with 2.872 (2) Å adjacent to the lone pair) supports this possibility [48]. In many lead(II) compounds, such an environment leaves space for close contact with another atom(s) and usually the researcher finds any potential donor center [48 –51]. However, in this structure, we observed the strong interaction between N8(s) of “p-2-minh” ligand(s) and the Pb center (Pb···N8 = 3.214(7), Pb-N8ⁱ = 3.214(7), Pb-N8ⁱⁱ = 3.219(7), Pb-N8ⁱⁱⁱ = 3.219(7), see Fig. 4). The distances between Pb–N are close to covalent bond.

There are C–H···N interactions and C–H···H interactions amongst the weak non-covalent contacts belonging to fragments of adjacent, distances values of these interactions (see Table 3) that suggest relatively strong interactions within this class of weak non-covalent contacts [52].

There are two different types of noncovalent π - π stacking interactions between the parallel aromatic rings belonging to adjacent chains, as shown in Fig. 5 The interplanar distance of the aromatic rings (Fig. 5) are 3.551 and 3.586 Å, appreciably shorter than the normal π - π stacking [52].

Consequently, the labile interactions also allow the the discrete molecular architecture interacts with neighbors and the structure extended to 3D supramolecular architecture (Fig. 6).

Thus, these factors, lone pair activity, labile and π - π stacking interactions, may control the coordination sphere of lead(II) ions in this complex. The obvious question then is whether the lone pair activity has stretched coordinate bonds to result in ligand stacking or whether it is the stacking interaction. However, one could say that the cooperative effect of the π - π interactions and the presence of the lone pair give a closer packing of the solved structure.

To examine the thermal stability of 1, thermogravimetric (TG) analysis and differential thermal analysis (DTA) were carried out between 10 and 780°C under argon flow (Fig. 7). The compound melts at 133°C. Then, the simultaneous removal of both “p-2-minh” ligands is observed exothermically in the range of 200–590°C, leading to formation of PbO.

3.1 DFT calculations

The calculated structural parameters are listed in Table 3. It should be noted that the experimental data belong to the solid phase, whereas the calculated data correspond to the isolated molecule in gas-phase. However, the experimental and computational data in Table 3 clearly show that both data only slightly differ from each other. For example, the largest difference between experimental and calculated Pb— N12 length is about 0.028 Å, while the largest deviation of ca. 2.20° occurs for the N12—Pb—N12ⁱ angle. As a result, the calculated geometrical parameters represent a good approximation.

The computed IR frequencies are listed in Table 1 together with the experimentally determined frequencies. The assignment of the ν(Pb–N) and ν(Pb–O) vibration are based on the theoretically calculated frequency with the frequency value 580 and 430 cm^–1 for a nickel complex [Pb(p-2-minh)₂].

The NBO charges of lead(II) and of the coordinated atoms were also calculated. The positive charge of the lead(II) ions was 1.418. The charges of the coordinated nitrogen atom of the “p-2-minh” ligands was –0.787 and –0.239, respectively, whereas the coordinated oxygen atom of the “p-2-minh” ligands was –0.787. The calculations indicate that 1 has 119 occupied molecular orbitals (MOs) per [Pb(p-2-minh)₂].unit. The value of the energy separation between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) was calculated. Figure 8 shows the HOMO and LUMO for the Pb(II) complex. As will be seen in Fig. 8, the HOMO of the title complex is principally localized on “p-2-minh” ligands whereas the LUMO is approximately delocalized on all atoms. The calculated HOMO–LUMO gap is 7.362 eV.

3.2 Nano-structure of lead(II) oxide

Nano-powders of lead(II) oxide were obtained from the decomposition of precursor 1 in oleic acid as a surfactant at 180°C, under an air atmosphere. Figure 9 shows the XRD pattern of PbO nano-oxide. All the diffraction peaks in this pattern can be well indexed to a cubic structure with a lattice constant of a = 5.9143(4) Å, which is consistent with the standard data file (JCPDS, No. 78-1897).

The morphology and size of the as-prepared PbO samples were further investigated using scanning electron microscopy (SEM). This process produced the regular shape of lead(II) oxide nano-particles with a diameter about 10 to 20 nm (Fig. 10).

4 Conclusion

In this work, sonochemical preparation of a novel nano lead(II) coordination compound containing pyridin-2-ylmethylene-isonicotinohydrazide ligand is described for first time, with a description of its use in the preparation of PbO nano-particles. The morphology of 1 prepared by the sonochemical method is composed of nano-sheets with a thickness of about 30 nm. The crystal structure of the complex has been also determined indicating that it takes the form of a discrete coordination compound in the solid state. With several supramolecular interactions the discrete unite interacts with neighbours and the structure extended to 3D supramolecular coordination polymer. A novel theoretical study of the title coordination compound was undertaken to examine its electronic structure, which allowed computations of bond distances and angles and vibrational frequencies in good agreement with the experimental data. The nano-structures of this coordination compound used as precursor in the preparation of PbO nanoparticles

Supplementary material

Crystallographic data for the structures reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication CCDC-1402297 for [Pb(p-2-minh)₂] (1). Copies of the data can be obtained by application to the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (Fax: +44-1223-336033, e-Mail: de-posit@ccdc.cam.ac.uk).

Footnotes

Acknowledgments

Support of this investigation by Yasuj University and Iran National Science Foundation (INSF, contract: 93023641) is gratefully acknowledged. The authors thank University of Qom for all the supports.

References

Lehn

J.-M.

, Angew Chem Int Ed Engl 27 (1988), 89.

Ahmad

, Chughtail

A.H.

, Younes

H.A.

and Verpoort

, Coord Chem Rev 280 (2014), 1–27.

Safarifard

and Morsali

, Coord Chem Rev 292 (2015), 1–14.

Abbasi

and Tarighi

, JNS 1 (2012), 89–93.

Gupta

, Sanotra

, Nawaz Sheikh

and Lal Kalsotra

, J Nanostructure Chem 3 (2013), 41.

Mosallanejad

, Int J Nano Dimens 5 (2014), 285–289.

Ansari

, Mosayebzadeh

, Arvand

and Mohammad-khah

, J Nanostructure Chem 3 (2013), 33.

Najafi

, Abbasi

A.M.

and Badiei

, JNS 2 (2012), 85–100.

Morsali

and Hashemi

, JNS 1 (2012), 89–93.

10.

Hashemi

, Tahmasian

, Morsali

and Abedini

, JNS 2 (2012), 163–168.

11.

Hosseyni Sadr

, Morsali

and Hojaghani

Sh.

, JNS 3 (2013), 109–114.

12.

Schmidt

, Casini

and Kühn

F.E.

, Coord Chem Rev 275 (2014), 19–36.

13.

Catalano

V.J.

, Malwitz

M.A.

and Etogo

, Inorg Chem 43 (2004), 5714–5724.

14.

Shimoni-Livny

, Glusker

J.P.

and Brock

C.W.

, Inorg Chem 37 (1998), 1853–1867.

15.

Ghasempour

, Azhdari Tehrani

and Morsali

, Ultrason Sonochem 27 (2015), 503–508.

16.

Derakhshandeh

P.G.

, Soleimannejad

and Janczak

, Ultrason Sonochem 26 (2015), 273–280.

17.

Hashemi

and Morsali

, Ultrason Sonochem 24 (2015), 146–149.

18.

Chung

J.-H.

, Min

B.-K.

, Kim

Y.K.

, Kim

K.-H.

and Kwon

T.-Y.

, J Mol Struct 1076 (2014), 698–703.

19.

Platas-Iglesias

, Esteban-Gomez

, Enriquez-Perez

, Avecilla

, deBlas

and Rodriguez-Blas

, Inorg Chem 44 (2005), 2224–2233.

20.

Nugent

J.W.

, Lee

, Reibenspies

J.H.

and Hancock

R.D.

, 91 (2015), 120–127.

21.

Shimonni-Livny

, Glusker

J.P.

and Bock

C.W.

, Inorg Chem 17 (1998), 1853.

22.

Walsh

and Watson

G.W.

, J Solid State Chem 178 (2005), 1422.

23.

Shaabani

, Mirtamizdoust

, Viterbo

, Croce

, Hammud

, Hojati-Lalemi

, Khandar

and Anorg

, Allg Chem 637 (2011), 713–719.

24.

Shaabani

, Mirtamizdoust

, Shadman

, Fun

H.K.

and Anorg

, Allg Chem 635 (2009), 2642–2647.

25.

Mirtamizdoust

, Shaabani

, Khandar

, Fun

H.K.

, Huang

, Shadman

, Hojati-Talemi

and Anorg

, Allg Chem 638 (2012), 844–850.

26.

Hanifehpour

, Mirtamizdoust

and Joo

S.W.

, J Inorg Organomet Polym 22 (2012), 916–922.

27.

Hanifehpour

, Mirtamizdoust

, Farzam

A.R.

and Joo

S.W.

, J Inorg Organomet Polym 22 (2012), 957–962.

28.

Mirtamizdoust

, Ali-Asgari

, Joo

S.W.

, Maskani

, Hanifehpour

and Oh

T.H.

, J Inorg Organomet Polym 23 (2013), 751–757.

29.

Hanifehpour

, Morsali

, Mirtamizdoust

and Joo

S.W.

, J Mol Struct 1079 (2015), 67–73.

30.

Mirtamizdoust

, Shalamzari

M.S.

, Behrouzi

, Florencio

M.H.

and Fun

H.K.

, J Inorg Organomet Polym 22 (2012), 1358–1364.

31.

Hanifehpour

, Mirtamizdoust

, Morsali

and Joo

S.W.

, Ultrason Sonochem 23 (2015), 275–281.

32.

Armstrong

C.M.

, Bernhardt

P.V.

, Chin

and Richardson

D.R.

, Eur J Inorg Chem (2003), 1145.

33.

Ghaedi

, Shahamiri

, Hajati

and Mirtamizdoust

, J Mol Liq 199 (2014), 483–488.

34.

Mercury 1.4.1, Copyright Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge, CB2 1EZ, UK, 2001–2005.

35.

Nakamoto

, Infrared and Raman Spectra of Inorganic and Coordination Compounds (Wiley, New York, 1997), 5th Edn., Part B, pp. 124–126.

36.

Harrowfield

J.M.

, Miyamae

, Skelton

B.W.

, Soudi

A.A.

and White

A.H.

, Aust J Chem 49 (1996), 1165–1169, and references therein.

37.

Bruker AXS Crystal Structure Analysis Package: Bruker (2000). SHELXTL. Version 6.14. Bruker AXS Inc., Madison, Wisconsin, USA. Bruker (2008). SADABS. Version 2008/1. Bruker AXS Inc., Madison, Wisconsin, USA. Bruker (2008). XPREP. Version 2008/2. Bruker AXS Inc., Madison, Wisconsin, USA. Bruker (2009). SAINT. Version 7.68A. Bruker AXS Inc., Madison, Wisconsin, USA. Bruker (2010). APEX2. Version 2010.3-0. Bruker AXS Inc., Madison, Wisconsin, USA.

38.

Cromer

D.T.

and Waber

J.T.

, International Tables for X-ray Crystallography; Kynoch Press: Birmingham, UK, 1974; Vol. 4, Table 2.2 A.

39.

Becke

A.D.

, J Chem Phys 98 (1993), 5648–5652.

40.

Lee

, Yang

and Parr

R.G.

, Phys Rev B 37 (1988), 785–789.

41.

Hay

P.J.

and Wadt

W.R.

, J Chem Phys 82 (1985), 270–283.

42.

A description of the basis sets and theory level used in this work can be found in the following: Foresman,

J. B.

; Frisch

A. E.

Exploring Chemistry with Electronic Structure Methods, 2nd ed.; Gaussian Inc.: Pittsburgh, PA, 1996.

43.

Frisch

M.J.

, et al., GAUSSIAN 98, Revision A.9, Gaussian Inc, Pittsburgh PA, 1998.

44.

Hashemi

and Morsali

, Ultrason Sonochem 24 (2015), 146–149.

45.

Hanifehpour

, Mirtamizdoust

, Morsali

and Joo

S.W.

, J Mol Struct 1079 (2015), 67–73.

46.

Akhbari

, Beheshti

, Morsali

, Bruno

and Amiri

, Rudbari, Inorg Chim Acta 423 (2014), 101–105.

47.

Hashemi

and Morsali

, Ultrason Sonochem 21 (2014), 1417–1423.

48.

Shimoni-Livny

, Glusker

J.P.

and Brock

C.W.

, Inorg Chem 37 (1998), 1853–1867.

49.

Casas

J.S.

and Sordo

, Lead chemistry, analytical aspects, environmental impact and health effects, First edition, Elsevier, San Diego, 2006.

50.

Frank

and Wittmer

F.-G.

, Chem Ber 130 (1997), 1731–1732.

51.

Jones

J.N.

and Cowley

A.H.

, Chem Commun (2005), 1300–1302.

52.

Hunter

C.A.

and Sanders

J.K.M.

, J Am Chem Soc 112 (1990), 5525–5534.

Stereochemically active lone pair on lead(II) nano 3D supramolecular network: Synthesis,structural characterization,thermal stability and DFT calculation of [Pb(p-2-minh) 2 ]

Abstract

Keywords

1 Introduction

2 Experimental

2.1 Materials and physical measurements

2.2 Preparation of nano structure and single crystal of [Pb(p-2-minh)2] (1)

2.3 Synthesis of lead(II) oxide nanoparticles

2.4 Crystallography

2.5 Computational details

3 Results and discussion

3.1 DFT calculations

3.2 Nano-structure of lead(II) oxide

4 Conclusion

Supplementary material

Footnotes

Acknowledgments

References

2.2 Preparation of nano structure and single crystal of [Pb(p-2-minh)₂] (1)