Synthesis, crystal structure and characterization of a new organic–inorganic hybrid material 4-(ammonium methyl) pipyridinium hexachloro stanate (II) trihydrate

Accepted Manuscript Synthesis, crystal structure and characterization of a new Organic–inorganic hybrid material 4-(ammonium methyl) pipyridinium hexachloro stanate (II) trihydrate

Mohamed Saber Lassoued, Mohammed.S.M. Abdelbaky, Abdelmajid Lassoued, Salah Ammar, Abdellatif Gadri, Abdelhamid Ben Salah, Santiago García-Granda PII:

S0022-2860(17)31496-5

DOI:

10.1016/j.molstruc.2017.11.023

Reference:

MOLSTR 24509

To appear in:

Journal of Molecular Structure

Received Date:

26 August 2017

Revised Date:

05 November 2017

Accepted Date:

07 November 2017

Please cite this article as: Mohamed Saber Lassoued, Mohammed.S.M. Abdelbaky, Abdelmajid Lassoued, Salah Ammar, Abdellatif Gadri, Abdelhamid Ben Salah, Santiago García-Granda, Synthesis, crystal structure and characterization of a new Organic–inorganic hybrid material 4(ammonium methyl) pipyridinium hexachloro stanate (II) trihydrate, Journal of Molecular Structure (2017), doi: 10.1016/j.molstruc.2017.11.023

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ACCEPTED MANUSCRIPT Highlights New hybrid compound, (C6H16N2) SnCl6.3H2O was synthesized at room temperature by slow evaporation. X-ray diffraction, SEM, IR, NMR, photoluminescence and thermal studies were reported.

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ACCEPTED MANUSCRIPT

Synthesis, crystal structure and characterization of a new Organic–inorganic hybrid material 4-(ammonium methyl) pipyridinium hexachloro stanate (II) trihydrate Mohamed Saber Lassoued, a, b, c* Mohammed. S. M. Abdelbaky, c Abdelmajid Lassoued, a Salah Ammar, a Abdellatif Gadri, a Abdelhamid Ben Salah, b and Santiago García-Granda c a

Unité de recherché Electrochimie, Matériaux et environnement UREME (UR17ES45), Faculté des Sciences de Gabès, Université de Gabès, Cité Erriadh, 6072 Gabès, Tunisie b

Material and Environment Science Laboratory, Science Faculty of Sfax University, P.B 1171, 3000 Sfax, Tunisia

C Department

of physical and analytical chemistry, Oviedo University-CINN, 33006 Oviedo, Spain

Corresponding author e-mail address: [email protected]

Abstract The present paper undertakes the study of (C6H16N2) SnCl6.3H2O which is a new hybrid compound. It was prepared and characterized by single crystal X-ray diffraction, X-ray powder, Hirshfeld surface, Spectroscopy measurement, thermal study and photoluminescence properties. The single crystal X-ray diffraction studies revealed that the compound crystallizes in monoclinic Cc space group with cell parameters a= 8.3309(9) Å, b= 22.956(2) Å, c=9.8381(9) Å, = 101.334(9) ° and Z=4. The atomic arrangement shows an alternation of organic and inorganic entities. The cohesion between these entities is performed via N– H···Cl, N-H···O, O–H···Cl and O-H···O hydrogen bonding to form a three-dimensional network. Hirshfeld surface analysis was used to investigate intermolecular interactions, as well 2D finger plots were conducted to reveal the contribution of these interactions in the

ACCEPTED MANUSCRIPT crystal structure quantitatively. The X-ray powder is in agreement with the X-ray structure. Scanning electronic microscopy (SEM) was carried out. Furthermore, the room temperature infrared (IR) spectrum of the title compound was recorded and analyzed on the basis of data found in the literature. Solid state 13C NMR spectrum shows four signals, confirming the solid state structure determined by X-ray diffraction. Besides, the thermal analysis studies were performed, but no phase transition was found in the temperature range between 30 and 450 °C. The optical and PL properties of the compound were investigated in the solid state at room temperature and exhibited three bands at 348 and 401 cm-1 and a strong fluorescence at 480 nm. Keywords: Crystal structure, IR absorption, SEM, Thermal stability, Optical transmission and Photoluminescence.

1. Introduction Organic–inorganic hybrid materials have received increasing attention in recent research because of their ability to combine the specific properties of inorganic frameworks (electronic properties, magnetic and dielectric transitions, substantial mechanical hardness and thermal stability) [1, 2] and the features of organic molecules (high fluorescence, structural diversity, plastic mechanical property…) [3–5]. Recently, a great attention has been devoted to the large family of organic–inorganic metal halides due to their special structural diversity and physical properties including interesting ideal thermal, excellent magnetic properties and mechanical stability, non linear optical activity and efficient luminescence [6–10]. It is therefore vital to design and synthesize hybrid compounds containing N-H bonds and explore their various properties. The materials based upon substituted complex ammoniums with halogenated metals such as Hg, Cd, Sn, and Cu etc. present very interesting physical properties [11-14]. In the case of stanate-halide systems, some interest has been directed towards halostanate (II) compounds in

ACCEPTED MANUSCRIPT combination with organic cations, due to potential semiconducting behavior [15,16], as well as the rich structural diversity displayed by these systems. In fact, the Sn (II) represents a potential class of materials with unusual structural archetypes. It is known that in p-block elements, there are non -bonding valence electrons on subvalent Sn (II) atoms which are commonly known as Inert-Pair-Effect. It should be noted that research in the field of organic-inorganic hybrid materials with pyridine and its derivatives has received considerable attention due to its interesting photochemical properties [17, 18]. Herein, we report the synthesis, crystal structure, Hirshfeld surface, spectroscopic measurements

(Fourier

Transform

Infrared

(FT-IR)

Spectroscopy,

optical

and

photoluminescence), Solid-state Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance (CP/MAS –NMR(13C CP-MAS NMR) spectra and thermal studies as well as

optical properties of a new organic material, 4-(ammonium methyl)

pipyridinium hexachloro stanate (II), (C6H16N2) SnCl6.3H2O.

2. Experimental 2.1. Preparation Single crystals of 4-(ammonium methyl) pipyridinium hexachloro stanate (II) trihydrate were prepared according to the following chemical equation: C6H14N2 +2HCl [C6H16N2]Cl2+SnCl4

H2O

[C6H16N2]2+ + 2Cl(C6H16N2) SnCl6.3H2O.

The first step was the preparation of 4-(amino methyl) pipyridine chloride (C6H14N2Cl2). ([C6H14N2]2+, 2Cl-) precipitates were then formed by the addition of an aqueous solution of HCl (38%) to 4-(amino methyl) pipyridine (C6H14N2) (0.0114 g, 0.1 mmol). The next step

ACCEPTED MANUSCRIPT was the formation of the desired compound: stoichiometric 1:1 amounts of [C6H16N2]Cl2 and SnCl4 (0.026 g, 0.1 mmol ) were dissolved in water. After 11 days, prismatic crystals were obtained by slow evaporation at room temperature. A single crystal suitable for X-ray diffraction analysis was selected and studied. 2. 2. Crystal chemistry The chemical analysis of Tin and chloride atoms was performed in order to confirm the formula determined by structural refinement [19]. Density was measured at room temperature by flotation in CCl4. The value of the density measured (Dm= 1.782 gcm-3) was very close to the calculated (Dx= 1.806 gcm-3). 2. 3. Investigation techniques The characterization of the prepared compound was performed using X-ray diffraction, Hirshfeld surface, Scanning electron microscope (SEM), Nuclear magnetic resonance (NMR), Infrared, Thermal and photoluminescence analyses. 2. 3.1. X-ray data collection A suitable colorless crystal of the title compound having dimensions of 0.24 × 0.13 × 0.10 mm3 was chosen for the structure determination and refinement. Indeed, it was selected under a polarizing microscope and mounted on a glass fiber. The crystal structure was determined from the single-crystal X-ray diffraction data collected at room temperature using a Bruker AXS CCD area detector system equipped with graphite monochromatic MoKa radiation (0.71073 Å). Lattice parameters were refined from the setting angles of 161 reflections in the 2.7 < θ < 31.4 range. The empirical absorption corrections were based on a multi-scan. A total of 13203 reflections were collected using the scan technique of which 3707 had I > 2ϴ(I) and were then used for structure determination. The structure analyses were carried out with the monoclinic symmetry, space group Cc according to the automated search for space group

ACCEPTED MANUSCRIPT available in WinGX [20]. The Tin atom was located using the Patterson methods with program SHELXS-86 [21]. The oxygen atoms and the organic moieties were found from successive Fourier calculations using SHELXL-97. All the hydrogen atoms were placed geometrically and refined isotropically. The pertinent experimental details of the structure determination for the new compound are presented in Table 1. The refinement was done by full-matrix least squares methods (SHELXL-97 program) and converged to an acceptable final agreement factor .The last cycle of refinement included the atomic coordinates for all the atoms, anisotropic thermal and isotropic thermal parameters whose values are listed in Table 2 and Table 3, respectively. The structural graphics of the asymmetric unit were created with ORTEP [22] for Fig. 1a and with the DIAMOND program [23] for the other figures. 2. 3.2. X-ray powder The X-ray powder diffraction (PXRD) was recorded on a Siemens D5000 powder diffractometer using Cu-Ka radiation (1.542 Å) with a 2θ range of 5–50°. The simulation of the PXRD spectra was carried out by the single-crystal data and Oscail (4.6.1) program. 2. 3.3. Micrographs and X-ray microanalysis Scanning electron microscope (SEM) and Energy-dispersive X-ray spectroscopy (EDXS) were recorded with a JEOL- 6610LV electron microscope operating at 30 kV coupled with an Oxford X-Max microanalysis system (EDX). 2. 3.4. Solid-state Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance (CP/MAS-RMN) Spectroscopy The 13C MAS NMR spectra were recorded at room temperature by means of a Brucker DSX300 spectrometer. The spectra were acquired with the use of cross-polarization for protons with 12 ms contact time. A powdered sample was packed in a 4 mm diameter rotor and set to

ACCEPTED MANUSCRIPT rotate at a speed of up to 8 kHz in a Doty MAS probe head. The chemical shifts were referenced with respect to dimethyl sulfoxide (DMSO).

2. 3.5. Spectroscopic measurements The infrared measurement was used to identify the functional groups and to determine the molecular structure of the prepared compound. The infrared spectra were obtained using a Nicole Impact 410 FT-IR spectrophotometer with a sample depressed in KBr pellet in the 400–4000 cm−1. Moreover, optical absorption spectra of the compound were measured at room temperature using a conventional UV–vis absorption spectrometer (Shimadzu UV 3101). Solid photoluminescence spectra were recorded using a time-resolved Edimbugh Instruments FLSP920 spectrofluorimeter with a Red-PMT detector and a Xenon bulb as an excitation source. 2. 3.6. Thermal analysis The thermogravimetric and differential thermal analyses were coupled using TGA Q500 TA instrument. The powder sample (16 mg) was heated starting from 30 °C, reaching 450 °C using a heating rate of 5 °C/min under vacuum atmosphere.

3. Results and discussion 3. 1. Description of the structure The title compound was obtained using the slow evaporation method at room temperature. The crystallographic analysis revealed that the complex crystallized in the monoclinic system, space group Cc, the unit cell parameters were: parameters a= 8.3309(9) Å, b= 22.956(2) Å, c=9.8381(9) Å, = 101.334(9) °, Z=4 and V = 1844.8(3) Å3.

ACCEPTED MANUSCRIPT The asymmetric unit was composed of one (C6H16N2)

2+

cation, one (SnCl6)2- and three

molecule of water (Fig. 1). Regarding the stanate atom, Sn, it occupies the special position on the twofold axis of the Cc space group. The coordination geometry of the Sn atom shows a slightly distorted octahedron formed by the Cl1, Cl2, Cl3, Cl4, Cl5, Cl6 atoms. The [SnCl6]2entities were located at x = 1/4, x = 3/4 (Fig. 2). The bond distances between Sn-Cl ranged from 2.4088 (2) to 2.4417 (3) Å with an average of 2.4286Å and the Cl-Sn-Cl angle varied between 89.50 (9)° and 179.14 (11)° and deviate slightly from the ideal octahedral values (90° and 180°). The average values of the distortion parameters of SnCl62-octahedron were calculated using respectively equations (1)-(2) [24].

ID (Sn-Cl) =

n16

 i 1

ID (Cl-Sn-Cl) =

di  dm n1dm

n 2 12

ai  am

i 1

n2 am



(1)

(2)

where d is the (Sn-Cl) distance, a is the (Cl-Sn-Cl) angle, m is the average value, n1 = 6, and n2 = 12. The values of the distortion indices were ID (Sn-Cl) = 0.00065(8) and ID (Cl-Sn-Cl) = 0.01323(1). The low values of the distortion indices indicate that the coordination geometry of the metal is a slightly distorted octahedral; this can be explained by the stereochemical inactivity of the 5s2 lone pair of Sn (IV).The projection of the atomic arrangement of (C6H16N2) SnCl6.3H2O prolonged following the a-axis (Fig. 2). The organic group was located in the (b, c) plane at approximately x = 0 and x = 2/4. Besides, the [SnCl6]2- anions and water molecules were arranged in parallel layers separated by the (C6H16N2)2+ cations. The organic part of the (C6H16N2) SnCl6.3H2O compound was formed by one type of cation, i.e. (C6H16N2) 2+. The selected measured bond lengths and bond angles are grouped in Table

ACCEPTED MANUSCRIPT 4. The organic molecule exhibited a regular spatial configuration with normal C-C and C-N distances in the range between 1.4672 (16) and 1.5323 (15) Å respectively and C-C-C and CC-N angles which were in the range between 110.09(8)° and 112.02(9)°, respectively. These values are in good agreement with those observed in similar compounds [24] and [25]. The weak intermolecular hydrogen bonding contacts N–H···Cl, N-H···O, O-H···Cl and OH···O reported in Table 5 and Fig. 3, provide a linkage between the cationic (C6H16N2)2+ entities, (SnCl6)2- anions and water molecules. The N···Cl, O···Cl, N···O and O···O distances varied between 2.764Å and 3.589Å and the N-H-Cl, O-H-Cl and O-H-N angle values varied from 117.00° to 174.92° [26, 27]. 3. 2. Hirshfeld surfaces The Hirshfeld surfaces [28, 29] and the associated 2D finger plots [30- 32], which accepts a structure input file in the CIF format serve as a powerful tool for gaining additional information about intermolecular interaction. They were calculated using crystal Explorer program [33] based on the results of X-ray studies. The value of d norm is negative or positive when intermolecular contacts are shorter or longer than van der Waals (vdw) radii, respectively. The d norm values are mapped onto the Hirshfeld surface using a red–blue–white color scheme: red regions represent closer contacts and a negative d norm value; blue regions represent longer contacts and a positive d norm value; and white regions represent a distance of contacts exactly equal to the vdw separation with a d norm value of zero. The molecular Hirshfeld surfaces of the title compound were generated using a standard (high) surface resolution with the 3D d norm surfaces, the distance to the nearest nucleus inside the surface “di” and the distance to the nearest atoms outside “de”, shape index and

ACCEPTED MANUSCRIPT curvedness mapped over a fixed color scale of -0.529 (red) to 1.263 Å (blue), from 0.786 to 2.601 Å and 0.788 to 2.607 Å, -1 to 1 Å and -4 to 0.4 Å, respectively (Fig. 4). The 2D fingerprint maps of 4-(ammonium methyl) pipyridinium hexachloro stanate (II) trihydrate (C6H16N2) SnCl6.3H2O provide some quantitative information about the individual contribution of the intermolecular interaction in the asymmetric unit (Fig. 5). Globally, H···Cl Cl···H and H···H intermolecular interactions were most abundant in the crystal packing (58.3% and 20.8%, respectively). It is evident that van der Waals forces exert an important influence on the stabilization of the packing in the crystal structure. Other intercontacts, i.e. O···H/H···O (7.8%), Cl···Cl (1.7%) and O···Cl/Cl···O (1.5%), contribute less to the Hirshfeld surfaces. On the other hand, the relative contributions of the different interactions to the Hirshfeld Surfaces were also calculated for the title compound (Fig. 6). 3.3. Molecular electrostatic potential The molecular electrostatic potential (MEP) is an important property that can be derived from electron density distribution. MEP is generated using the Avogadro software [34], on an asymmetric unit. The MEP is used to determine the electrophilic and nucleophilic attacks during the reactions as well as hydrogen bonding interactions. Moreover, blue and red colors indicate the positive and negative potentials, respectively. Fig. 7 shows that a positive electrostatic potential is localized over the organic cation and molecular water while the SnCl6 part is more electronegative. Based on this result we can say that there is a global electrostatic attraction between the SnCl6 anion water molecules and the organic cation which adds up to the favorable H⋯Cl and H⋯O hydrogen bonding.

ACCEPTED MANUSCRIPT 3. 4. X-ray Power Diffraction (XRPD) analysis To confirm the phase purity of the (C6H16N2) SnCl6.3H2O compound, the XRPD patterns were compared with the patterns generated from the single crystal data (Fig. 8). It can still be well considered that the bulk synthesized materials and the crystals used for diffraction are homogeneous. 3. 5. Scanning Electron Microscopic (SEM-EDXS) The morphology of 4-(ammonium methyl) pipyridinium hexachloro stanate (II) trihydrate crystals obtained with the scanning electron microscopy (SEM) is shown in Fig. 9(a.b). As can be seen from this figure, the compound consists of an assembly of crystal fragments having uniform distribution and a flat surface which indicates good crystal quality. The EDX spectrum of the title compound revealed the presence of all non-hydrogen atoms: Stanate, Chloride, Carbon, Nitrogen and Oxygen. Elemental analyses for the observed atoms were C: 15.4%, N: 6.1%, Sn: 25%, Cl: 43.6% and O: 9.8% while the calculated values were C: 15.01%, N: 5.83 %, Sn: 24.74 %, Cl: 44.40 % and O: 10.00% (Fig. 9(c)). 3. 6. Infrared Spectroscopy To gain more information on the crystal structure, we have undertaken a vibrational study using infrared spectroscopy. The infrared spectrum of the title compound is showing in Fig. 10. Using previous works reported in the literature on similar compounds [35-37]; we propose in Table 6 an attempt of assignment of the main bands. The IR spectrum of (C6H16N2) SnCl6.3H2O shows at high wavenumbers an absorption centered at 3387 and 3322 cm-1 are assigned to (OH) vibration of the water molecules forming the hydrate. The dynamics of the NH group in the organic part predicts the presence of several and dispersed vibrational normal modes due to their participation in several

ACCEPTED MANUSCRIPT hydrogen bonds types. In the infrared spectrum, the bands located at 3221 and 3121 cm-1 correspond respectively to the asymmetric and symmetric vibrations of the NH stretching bands. The bands at 3020and 2990 cm_1 were associated with the (C–H) of the aromatic ring. Moreover, bands observed at 1627 cm-1 and 1591 cm-1 are identified as scissoring vibrations of the NH3 group while the corresponding rocking mode is observed at 1068 cm-1. As mentioned in Table 6, the stretching, scissoring and rocking vibrations of the CH2 group take apart in both spectra. Furthermore, we note that some characteristic bands related to the protonated amine group appear in the infrared spectrum at 1141, 986, 766, 536 and 490 cm-1. 3. 7. Solid state NMR spectroscopy The experimental spectrogram of high resolution nuclear magnetic resonance of the 13C CPMAS NMR of (C6H16N2) SnCl6.3H2O is shown in Fig. 11. NMR exhibited four signals with respect to four different carbon environments. This shows the existence of own organic cations in the asymmetric unit of the compound. From the spectrum, a signal of about 26.19 ppm corresponds to the carbon atoms C (2) and C (5). The next signal of 32.03 ppm is attributed to the C (1) carbon atom. Finally, the two higher chemical shift values,42.75 and 43.44 ppm, can be explained by the fact that C(3)/C(4) and C(6) are linked to two electronegative atoms N(1) and N(2),while the peaks at 40 ppm correspond to the presence of DMSO (Table 7). These results are in good agreement with the crystallographic data. 3. 8. Thermal study The DTA measurements and TGA analyses were carried out to characterize the thermal stability of the hybrid compound with a heating rate of 5°C/min between 30 and 450°C under investigation, presented in Fig. 12.

ACCEPTED MANUSCRIPT In the experimental temperature ranging from 30 to 450 °C, the TGA curve exhibited a whole weight loss of 75.24% subdivided into two weight loss stages. The first, which occurred in the temperature range of 30–120°C, is related to the endothermic peaks of the DTA curve and corresponds to the removal of three water molecules, thus leading to the anhydrous phase (C6H16N2) SnCl6 (experimental weight loss: 9.9% and calculated weight loss: 10.76%). The second loss, which was in the temperature range of 300–450°C, corresponds to the degradation of the organic entity and the release of chloride molecule arising from an intermolecular elimination reaction (experimental weight loss: 67% and calculated weight loss: 71%). A black deposit of carbon was obtained at the end of the experience. 3. 9. Optical and photoluminescence study The optical absorption spectrum of the title compound films measured at room temperature shown in Fig. 13 exhibits two distinct absorption bands centered at 348 cm-1 and 401 cm-1. This is very similar to results found in other previous studies in the literature containing organic-inorganic compound films [38, 39]. The lower energy absorption peak at 401 cm-1 is due to band gap absorption and it is assigned to the excitation of free electron–hole pairs within the [SnCl6]2- inorganic part. Under excitation, an electron is excited from the valence band to the conduction band, leaving a hole in the valence band. The electron transition back to the ground state that is the recombination of the electron and hole yields an emission, which suggests that the material behaves as semiconductor and is consistent with the dark red of the crystal [40-42]. The peak which occurred at 348 cm-1 can be attributed to the absorption of the highest energetic level in the conduction band.

ACCEPTED MANUSCRIPT The optical band gap (Eg) for 4-(ammonium methyl) pipyridinium hexachloro stanate (II) trihydrate can be determined by extrapolation from the absorption edge which is given by the following equation [43]. (αhν) n =A (hν-Eg) (3) Where α is the absorption coefficient, A is constant, hν is the energy of light and n is a constant depending on the nature of the electron transition [44]. (C6H16N2) SnCl6.3H2O has two band gap at 3.56eV and 3.09 eV contributed to two absorption band at 348 and 401 cm-1 respectively (Fig. 13(b)). On the other hand, the photoluminescence spectrum (Fig. 14) shows a broad and strong band of luminescence located at 2.58 eV (480 nm), which can be even observed with enaided eye at room temperature and is due to exciton emission. The luminescence originates from electronic transitions within the chlorostanate inorganic part SnCl6. In the Stanate (II) chloride based hybrids, the lowest exciton state arises from excitations between the valence band, which consists of a mixture of Sn (5s) and Cl(4p) states, and the conduction band, which derives primarily from Sn(5p) states [45, 46] . A simple model illustrating the formation and recombination process of the exciton in (C6H16N2) SnCl6.3H2O is shown in Scheme 1. Under the excitation of 375 nm irradiation, an electron (-) is excited from the valence band (VB) to the conduction band (CB), leaving a hole (+) in the VB. The electron (_) and the hole (+) move freely in the CB and VB, forming an exciton. The recombination of the electron and hole in the exciton yields a red emission at 480 nm (Fig. 15).

4. Conclusion We successfully fabricated a special inorganic–organic hybrid, 4-(ammonium methyl) pipyridinium hexachloro stanate (II) trihydrate (C6H16N2) SnCl6.3H2O. This new organic– inorganic compound crystallized in the monoclinic system with Cc space group at room

ACCEPTED MANUSCRIPT temperature, whose structural arrangement can be described as an alternation of organicinorganic layers that is performed via N-H···Cl, N-H···O, O-H···Cl and O-H···O hydrogen bonding. Hirshfeld surface fingerprint plots showed different types of intermolecular interactions including hydrogen bonding. The powder XRD was homogeneous with singlecrystal. The vibrational properties of this compound were studied by infrared spectroscopy. The numbers of the 13C CP-MAS NMR components are in full agreement with the ones of the crystallographically independent carbon sites. The (TGA/DTA) thermal analyses were performed to establish the thermal stability of the crystal. Moreover, the studies of optical and luminescence activities revealed that this compound exhibited a two-band absorption and a strong fluorescence property at room temperature. Supporting information available Crystallographic data for the structural analysis have been deposited with the Cambridge Crystallographic data Center, CCDC 1570004 for the complex. Copies of the data can be obtained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html. Acknowledgments Financial support from Faculty of Science in University of Gabes, Tunisia,

Spanish

Ministerio de Economía y Competitividad (MINECO-13-MAT2013-40950-R, and FPI grant BES-2011-046948 to MSM.A.) and Gobierno del Principado de Asturias (GRUPIN14-060) are acknowledged.

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ACCEPTED MANUSCRIPT [29] M.A. Spackman, J.J. McKinnon, Cryst. Eng. Comm. 4 (2002) 378-392. [30] M. S. Lassoued, Mohammed S. M Abdelbaky, A. Lassoued, A. Gadri, S. Ammar, A. Ben Salah, S. Garcia Granda, J. Mol. Struct. 1141 (2017)390-399. [31] S.K. Seth, G.C. Maity, T. Kar, J. Mol. Struct. 1000 (2011) 120-126. [32] M. S. Lassoued, W. Ben Soltan, Mohammed S. M. Abdelbaky, S. Ammar, A. Gadri, A. Ben Salah, S. Garcia Granda, J. Matter. Sci. 28 (2017)12698-12710. [33] S.K. Wolff, D.J. Grimwood, J.J. McKinnon, D. Jayatilaka, M.A. Spackman, CrystalExplorer 2.1, University of Western Australia, Perth, Australia (2007). [34] M. D. Hanwell, D. E. Curtis, D. C. Lonie, T. Vandermeersch, E. Zurek, G. R, Hutchison, J. Cheminform. 4 (2012) 1-17. [35] A. Tounsi, B. Hamdi, R. Zouari, A. Ben Salah, Physica E. 84 (2016) 384-394. [36] C. Hrizi, A. Trigui, Y. Abid, N. Chniba-Boudjada, S. Chaabouni, P. Bordet, J. Sol. State. Chem. 184 (2011) 3336-3344. [37] R. Hajji, A. Oueslati, N. Errien, F. Hlel, Polyhedron. 79 (2014) 97-103. [38] Y. Zhou,J. Li, H. Liu, L. Zhao, H. Jiang. Tetrahedron Lett. 47 (2006) 8511-8514. [39] A. Kessentini, M. Belhouchet, J.J. Suñol, Y. Abid, T. Mhiri, J. Luminescence. 149 (2014) 341-347. [40] C. Hrizi, N. Chaari, Y. Abid, N.C. Boudjada, S. Chaabouni, Polyhedron. 46 (2012) 4146. [41] A. Kessentini, M. Belhouchet, J.J. Sunol, Y. Abid, T. Mhiri, J. Luminescence. 134 (2015) 28-33.

ACCEPTED MANUSCRIPT [42] A.C. Dhieb, A. Valkonen, M. Rzaigui, W. Smirani, J.Mol.Struct. 1102 (2015) 50-56. [43] R. Branek, H. Kisch, Photochemical and Photobiological Sciences. 7 (2008) 40-48. [44] J. I. Pankove, Prentice-Hall Inc. Englewood Cliff, New Jersey. (1971), 34-86. [45] H.F. Chen, M.J. Zhang, M.S. Wang, W.B. Yang, X.G. Guo, C.Z. Lu, Inorg. Chem. Communications. 23 (2012) 123-126. [46] H. Dammak, A. Yengui, S. Triki, Y. Abid, J. luminescence. 161(2015) 214-220. Table Captions

Table 1 Crystal data and structure refinement for (C6H16N2) SnCl6.3H2O crystal. Table 2 Atomic coordinates and equivalent thermal factors of agitation Ueq (Å2) and isotropic Uiso (Å2)* in (C6H16N2) SnCl6.3H2O Table 3 Factors of anisotropic thermal agitation of (C6H16N2) SnCl6.3H2O Table 4 Selected bond distances [Å] and angles [°] in (C6H16N2) SnCl6.3H2O crystal. Table 5 Main interatomic distances (Å) and bond angles (°) involved in hydrogen bonds (e.s.d. are given in parentheses). Table 6 Observed vibration frequencies (cm−1) and band assignments for (C6H16N2) SnCl6.3H2O Table 7 The chemical shifts of the carbons atoms in the SnCl6.3H2O Figure Captions Fig. 1 Asymmetric unit of (C6H16N2) SnCl6.3H2O

13C

NMR spectrum of (C6H16N2)

ACCEPTED MANUSCRIPT Fig. 2 View of an inorganic-organic sheet in (C6H16N2) SnCl6.3H2O Fig. 3 Perspective view of the (C6H16N2) SnCl6.3H2O compound (the red lines represent hydrogen bonds) Fig. 4 Hirshfeld surface analysis of (C6H16N2) SnCl6.3H2O (a) dnorm (b) de (c) di (d) Curvedness (e) Shape-index Fig. 5 Fingerprint plots of major contacts in (C6H16N2) SnCl6.3H2O Fig. 6 The relative contributions to the Hirshfeld surface area for (C6H16N2) SnCl6.3H2O Fig. 7 Electrostatic potential (red: negative potential, blue: positive potential) Fig. 8 Simulated and Experimental XRD of (C6H16N2) SnCl6.3H2O Fig. 9 SEM images (a, b) and a typical EDX spectrum (c) of (C6H16N2) SnCl6.3H2O Fig. 10 FT-IR spectra of (C6H16N2) SnCl6.3H2O Fig. 11 13C CP-MAS NMR spectrum of (C6H16N2) SnCl6.3H2O in DMSO Fig. 12 TGA- DTA heating of (C6H16N2) SnCl6.3H2O compound Fig. 13 Optical absorption spectra of (C6H16N2) SnCl6.3H2O (a) Tauc plot obtained from UVVis DRS spectra of (C6H16N2) SnCl6.3H2O (b) measured at room temperature. Fig. 14 Excitation and Emission fluorescence profile of (C6H16N2) SnCl6.3H2O Fig. 15 Simple model for the formation and recombination of the exciton in (C6H16N2) SnCl6. 3H2O

ACCEPTED MANUSCRIPT Figures Fig. 1

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Hirshfeld surfaces %

70 60 50 40 30 20 10 0 H…Cl/Cl…H

H…H

O…H/H…O

Cl…Cl

Intermolecular interactions

O…Cl/Cl…O

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Fig. 7

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Fig. 8

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Fig. 9

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ACCEPTED MANUSCRIPT Fig. 11

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ACCEPTED MANUSCRIPT Fig. 13 (a, b)

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Sheme 1. Recombination process in 4-(ammonium methyl) pipyridinium hexachloro stanate (II) trihydrate

ACCEPTED MANUSCRIPT Tables: Table 1 Compound

(C6H16 N2) SnCl6.3H2O

Color/shape

Incolorless/prismatic

Space group Température (°C) Cell constants

Cc 25

a (Å) b (Å) c (Å) β (deg) Cell volume (Å3) Formula units/unit cell Dcalc (g cm−3)

8.3309(9) 22.956 (2) 9.8381 (9) 101.334 (9) 1844.8 (3) 4 1.806

Diffractomètre/scan Radiation, graphite monochromator

Enraf–Nonius Kappa CCD Mo-Kα (λ=0.71216 Å)

Max, Crystal dimensions (mm) μcalc (mm−1) Unique reflections θ range (deg)

0.24×0.13×0.10 2.25 5395

Reflections with I>2σ(I) a Range of h, k, l F(000)

3707 ±12, ±33, ±14 992

Weight

1/[σ2(Fo2) + (0.0842P)2], where P=max[(Fo2,0)+2Fc2]/3 0.074 0.18 1.03

R=∑||Fo−Fc||/∑|Fo| Rw Goodness-of-fit on F2 a:

Corrections of Lorentz polarization.

2,7 ⩽θ⩽ 31.4

ACCEPTED MANUSCRIPT Table 2 ATOM

x

Y

z

Ueq

Sn1 Cl4 Cl2 Cl5 Cl6 Cl3 Cl1 N2 H2A H2B O1 H1Q H1R O2 H2S H2T O3 H3U H3V C2 H3 H2 C1 H1 C6 H10 H11 C3 H5 H4 N1 H1B H1A H1C C4 H7 H6 C5 H9 H8

0.90674(8) 1.13629(3) 0.93461(3) 0.87409(4) 0.72070(3) 1.09246(4) 0.67449(4) 0.64217(14) 0.70167 0.70956 0.83859(8) 0.82203 0.85029 -0.03362(6) -0.06552 0.05611 -0.13582(7) -0.09596 -0.21260 0.46944(12) 0.54009 0.42118 0.33405(12) 0.25996 0.23495(13) 0.30746 0.15643 0.56991(15) 0.65638 0.50046 0.14761(16) 0.10509 0.06769 0.21708 0.51128(15) 0.56158 0.44305 0.40764(15) 0.31997 0.47313

0.62927(2) 0.68875(11) 0.57150(10) 0.68667(10) 0.69435(12) 0.56336(12) 0.56910(13) 0.37624(4) 0.36350 0.39558 0.43997(3) 0.43939 0.47496 0.30079(2) 0.26565 0.30208 0.17931(3) 0.14510 0.18138 0.34665(5) 0.36651 0.31334 0.38803(5) 0.36623 0.41143(5) 0.43121 0.43969 0.32605(5) 0.30033 0.30433 0.36487(5) 0.34017 0.38027 0.34593 0.41656(5) 0.44940 0.39628 0.43824(5) 0.46199 0.46259

0.49970(7) 0.60953(2) 0.71060(2) 0.29110(2) 0.58918(3) 0.41536(3) 0.39250(3) 0.36367(11) 0.30256 0.43148 0.58426(9) 0.66679 0.55981 0.40290(8) 0.40370 0.37416 0.36418(8) 0.37105 0.40957 0.52768(10) 0.60373 0.56517 0.45819(11) 0.38629 0.55984(12) 0.63489 0.51326 0.42343(14) 0.46894 0.35001 0.6172512) 0.55005 0.65384 0.68270 0.29229(12) 0.25476 0.21557 0.38799(12) 0.33662 0.45835

0.04152(17) 0.05318(6) 0.05238(6) 0.05418(6) 0.05752(7) 0.06627(8) 0.06972(9) 0.05105(3) 0.06126 0.06126 0.07048(2) 0.10572 0.10572 0.07209(2) 0.10813 0.10813 0.07302(2) 0.10953 0.10953 0.05139(2) 0.06167 0.06167 0.04853(2) 0.05823 0.05863(3) 0.07036 0.07036 0.06974(3) 0.08368 0.08368 0.06456(3) 0.07747 0.07747 0.07747 0.06611(3) 0.07934 0.07934 0.06252(3) 0.07502 0.07502

ACCEPTED MANUSCRIPT [ Ueq=1/3∑i∑j Uij ai* aj* ai aj] The formula of Factors of anisotropic thermal agitation is exp[−π2{h2a∗2U11 + k2b∗2U22 + l2c∗2U33 + 2hka∗b∗U12 + 2hla∗c∗U13 + 2klb∗c∗U23}],with a∗, b∗ and c∗ reciprocal crystallographic parameters. Table 3 ATOM

U11

U22

U33

U23

U13

U12

Sn1 Cl4 Cl2 Cl5 Cl6 Cl3 Cl1 N2 O1 O2 O3 C2 C1 C6 C3 N1 C4 C5

0.04913(3) 0.05853(16) 0.06663(16) 0.07304(17) 0.05979(16) 0.08909(2) 0.07521(2) 0.04831(6) 0.08653(6) 0.07813(6) 0.06038(5) 0.05250(6) 0.04016(5) 0.05178(7) 0.06746(8) 0.05243(7) 0.06983(8) 0.06228(7)

0.04163(3) 0.05390(14) 0.04963(13) 0.05106(13) 0.06383(16) 0.05587(15) 0.06535(17) 0.06733(7) 0.06092(5) 0.07628(5) 0.09969(6) 0.05445(6) 0.05820(6) 0.07078(7) 0.06252(7) 0.09648(9) 0.07073(7) 0.07154(7)

0.03315(3) 0.04387(13) 0.04099(13) 0.03703(12) 0.04991(14) 0.05808(16) 0.06005(18) 0.04041(5) 0.05959(5) 0.05707(5) 0.05675(5) 0.05193(6) 0.04668(6) 0.06022(7) 0.08378(9) 0.04638(6) 0.05654(7) 0.05348(7)

0.00193(3) 0.00313(10) 0.01029(10) 0.00746(10) 0.00795(11) 0.00394(12) 0.00397(13) -0.00745(4) -0.00364(4) 0.00201(4) 0.00153(4) 0.01132(5) -0.00445(5) -0.00612(5) 0.00093(6) 0.00130(5) 0.01172(5) 0.02662(5)

0.00650(2) 0.00211(11) 0.01083(11) 0.00738(11) 0.01316(12) 0.02479(15) -0.00076(14) 0.01583(4) 0.00361(4) 0.00158(4) 0.00605(4) 0.02173(5) 0.00720(4) 0.02784(5) 0.02601(7) 0.01364(5) 0.00938(6) 0.01076(5)

-0.00027(3) -0.01118(12) 0.00314(11) 0.00216(12) 0.01609(13) 0.02257(14) -0.02382(15) -0.00878(4) 0.00244(4) -0.01748(4) -0.00903(4) -0.00452(5) -0.00197(5) -0.00709(6) -0.00631(6) -0.00012(5) -0.01091(6) 0.00019(6)

ACCEPTED MANUSCRIPT Table 4 Octahedron SnCl6 Distances(Å) Angles(°) Sn1-Cl5 2.4088 (2) Cl3-Sn1-Cl5 91.29 (10) Sn1-Cl3 2.4242 (3) Cl4-Sn1-Cl5 91.07 (9) Sn1-Cl4 2.4242 (2) Cl2-Sn1-Cl5 178.98 (11) Sn1-Cl2 2.4348 (2) Cl6-Sn1-Cl5 89.95 (9) Sn1-Cl6 2.4383 (3) Cl1-Sn1-Cl5 89.67 (10) Sn1-Cl1 2.4417 (3) Cl4-Sn1-Cl3 90.20 (11) Cl2-Sn1-Cl3 89.50 (9) Cl6-Sn1-Cl3 178.76 (10) Cl1-Sn1-Cl3 90.23 (11) Cl2-Sn1-Cl4 89.56 (9) Cl6-Sn1-Cl4 89.75 (10) Cl1-Sn1-Cl4 179.14 (11) Cl6-Sn1-Cl2 89.26(9) Cl1-Sn1-Cl2 89.70(9) Cl1-Sn1-Cl6 89.80 (11) Organic cation and water molecules Distances(Å) Angles(°) Distances(Å) N2-C3 1.4748 (15) C4-N2-C3 110.71 (10) C3-C2 1.5210 (16) N2-C4 1.4960 (16) H2A-N2-C3 109.50 C3-H5 0.9700 N2-H2A 0.9000 H2B-N2-C3 109.50 C3-H4 0.9700 N2-H2B 0.9000 H2A-N2-C4 109.50 N1-C6 1.4672 (16) O1-H1Q 0.8500 H2A-N2-C4 109.50 N1-H1B 0.8900 O1-H1R 0.8494 H2B-N2-H2A 108.07 N1-H1A 0.8900 O2-H2S 0.8498 H1R-O1-H1Q 109.54 N1-H1C 0.8900 O2-H2T 0.8501 H2T-O2-H2S 109.46 C4-C5 1.4829 (18) O3-H3U 0.8501 H3V-O3-H3U 109.41 C4-N2 1.4960 (16) O3-H3V 0.8503 C1-C2-C3 110.31(9) C4-H7 0.9700 C2-C3 1.5210 (16) H3-C2-C3 109.59 C4-H6 0.9700 C2-C1 1.5293 (13) H2-C2-C3 109.59 C5-C4 1.4829 (18) C2-H3 0.9700 H3-C2-C1 109.59 C1-C5 1.5323 (15) C2-H2 0.9700 H2-C2-C1 109.59 H9-C5 0.9700 C1-C6 1.5148 (15) H2-C2-H3 108.13 H8-C5 0.9700 C1-C2 1.5293 (13) C2-C1-C6 112.02(9) C1-C5 1.5323 (15) C5-C1-C6 110.43(9) C1-H1 0.9800 H1-C1-C6 108.05 C6-N1 1.4672 (16) C5-C1-C2 110.09(8) C6-C1 1.5148 (15) H1-C1-C2 108.05 C6-H10 0.9700 H1-C1-C5 108.05 C6-H11 0.9700 C1-C6-N1 111.82(10) C3-N2 1.4748 (15) H10-C6-N1 109.25

Angles(°) H11-C6-N1 109.25 H10-C6-C1 109.25 H11-C6-C1 109.25 H11-C6-H10 107.93 C2-C3-N2 110.34(10) H5-C3-N2 109.59 H4-C3-N2 109.59 H5-C3-C2 109.59 H4-C3-C2 109.59 H4-C3-H5 108.12 H1B-N1-C6 109.47 H1A-N1-C6 109.47 H1C-N1-C6 109.47 H1A-N1-H1B 109.47 H1C-N1-H1B 109.47 H1C-N1-H1A 109.47 N2-C4-C5 111.79(9) H7-C4-C5 109.26 H6-C4-C5 109.26 H7-C4-N2 109.26 H6-C4-N2 109.26 H6-C4-H7 107.93 C1-C5-C4 111.60(10) H9-C5-C4 109.30 H8-C5-C4 109.30 H9-C5-C1 109.30 H8-C5-C1 109.30 H8-C5-H9 107.96

ACCEPTED MANUSCRIPT Table 5 D-H N2-H2A N2-H2A N2-H2A N2-H2B O1-H1Q O1-H1Q O1-H1R O1-H1R O2-H2S O2-H2T O3-H3U O3-H3V N1-H1B N1-H1A N1-H1A N1-H1A N1-H1C

d(D-H) 0.900 0.900 0.900 0.900 0.850 0.850 0.849 0.849 0.850 0.850 0.850 0.850 0.890 0.890 0.890 0.890 0.890

d(H..A) 2.515 2.656 2.739 1.954 2.748 2.982 2.683 2.929 2.082 2.820 2.825 2.541 1.895 2.340 2.764 2.851 2.041


d(D..A) 3.323 3.168 3.329 2.852 3.569 3.519 3.303 3.634 2.919 3.464 3.589 3.358 2.764 3.062 3.324 3.472 2.909

A Cl6(a) O2(b) Cl2(c) O1 Cl1(d) Cl3(e) Cl2 Cl1 O3 Cl4(f) Cl1(g) Cl4(h) O2 O1(i) Cl5(j) Cl3(k) O3(l)

a; [ x, -y+1, z-1/2 ]/ b; [ x+1, y, z ]/ c; [ x, -y+1, z-1/2 ]/ d; [ x, -y+1, z+1/2 ]/e; [ x, -y+1, z+1/2 ]/ f; [ x-1, -y+1, z-1/2]/ g; [ x-1/2, y-1/2, z]/ h; [ x-3/2, y-1/2, z]/ i; [ x-1, y, z ]/ j; [ x-1, -y+1, z+1/2]/ k; [ x-1, -y+1, z+1/2]/ l; [ x+1/2, -y+1/2, z+1/2]

ACCEPTED MANUSCRIPT Table 6 Wavenumbers cm-1 Tentative of assignments

IR

As(O-H)

3387

s(O-H)

3322

As(N-H+)

3221

s(N-H+)

3121

(C-H)

3020, 2990



1627, 1591

 (CH2)

1499, 1444

(CH2)

1361

 (C-N)

1141

 (C-C)

986

C

766

 (CCN)

536

 (CCC)

490

ν: stretching; : scissoring; t:twisting; ρ: rocking; t: torsion; a: asymetric, s:symmetric

ACCEPTED MANUSCRIPT Table 7 Peaks iso (ppm)

C5/C2 26.19

C1

C3/C4

C6

32.03

42.75

43.44