Journal of Science: Advanced Materials and Devices (2018) 113e121 Contents lists available at ScienceDirect Journal of Science: Advanced Materials and Devices journal homepage: www.elsevier.com/locate/jsamd Original Article Magnetic behavior and Raman spectroscopy of the composite system of CuCl2$2H2OeC12H9NO S Datta a, A.S Mahapatra a, P Sett b, M Ghosh c, P.K Mallick a, P.K Chakrabarti a, * a SSRL, Department of Physics, Burdwan University, Burdwan 713104, India Physics Department, Gobardanga Hindu College, N 24 Parganas 743273, India c Spectroscopy Department, Indian Association for the Cultivation of Science, Kolkata 700033, India b a r t i c l e i n f o a b s t r a c t Article history: Received 16 June 2017 Received in revised form 23 October 2017 Accepted 23 October 2017 Available online 28 October 2017 The metaleligand nanocomposite system of CuCl2-2-benzoyl pyridine (C12H9NO) was prepared by a chemical route and its crystallographic phase has been confirmed by analyzing the X-ray diffractograms The strain was developed in the composite due to the lattice mismatch of the two constituting components The composite exhibits a paramagnetic behavior in the temperature range of 14e300 K with an effective magnetic moment of about 1.923 mB This is attributed to the incomplete quenching of the orbital angular momentum Room temperature Raman spectra of the composite and the individual components, CuCl2$2H2O and 2-BOP have been analyzed along with their respective FTIR spectra These comparative studies have yielded some interesting information related to the structure of the composite The observed structural, morphological and spectroscopic properties are found compatible with those obtained from the magnetic studies © 2017 The Authors Publishing services by Elsevier B.V on behalf of Vietnam National University, Hanoi This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/) Keywords: Nanocomposite sample Chemical synthesis Raman and infrared spectroscopy Magnetic properties Introduction Preparation and investigation of physical properties of composite systems derived from organic molecules and transition metal ion based compounds is now-a-days an interesting field of research [1e5] The importances of the metal ion coordinated with the suitable bridging ligands are quite attractive for applications in different fields of physics, chemistry and biology For the synthesis of such compounds, different choices of organic molecules are considered of which aza aromatic and carbonyl complexes are of much interests due to their certain elusive photophysical [6], photochemical [7], and biological [8] properties, which have attracted the attention of many researchers for thorough investigations The distinguishing features of the photophysical and photochemical properties of aza complexes with respect to their hydrocarbon analogs arise due to the presence of some low lying np* states in the immediate neighborhood of the lowest singlet and triplet pp* states Pyridine derivatives are very useful compounds in different areas of both theoretical and experimental research For example, the 2-benzoylpyridine (2-BOP) and its derivatives have * Corresponding author Fax: ỵ91 3422530452 E-mail address: pabitra_c@hotmail.com (P.K Chakrabarti) Peer review under responsibility of Vietnam National University, Hanoi been found to be important as complexation agent for the spectroscopic determination of a great variety of metals [9] Also, syntheses of such compounds with benzoylpyridines are significant issues in coordination chemistry for the study of geometric isomerism and the reactivity of the isomers In the field of genomic and medicinal research, copper (II)-benzoylpyridine complexes are used for their DNA cleavage efficiency [10e14] Some works on different composites of 2-BOP with salts of different 3d transition metal ions are reported [15e21] In these investigations, no detailed studies on their magnetic properties and spectroscopic behaviors have been carried out Moreover, the preparation of these systems in the nano regime and the investigation on their thermophysical properties would be interesting to study the influence of the nanoparticles when compared with the respective entities of their bulk counterparts In this paper we present the preparation and investigations of the copper (II) chloride composite with the 2-BOP ligand in detail Metaleligand nanocomposite system of CuCl2-2-benzoyl pyridine (C12H9NO) was prepared by a chemical route and its phase formation was confirmed by X-ray diffraction and Field Emission Scanning Electron Microscopy (FESEM) analyses Due to the mismatch of the crystal structure of the individual components, strain was found to develop in the nanocomposite Structural morphology of the synthesized nanocomposite has also been studied The strain and the https://doi.org/10.1016/j.jsamd.2017.10.005 2468-2179/© 2017 The Authors Publishing services by Elsevier B.V on behalf of Vietnam National University, Hanoi This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/) 114 S Datta et al / Journal of Science: Advanced Materials and Devices (2018) 113e121 average particle size have been determined Magnetic properties of the composite have been investigated in a critical manner in the temperature range of 14e300 K Besides these, detailed investigation on the Raman and infrared spectra of the system and their comparative analyses with those of the free ligand [22] has been carried out to get a critical insight into the system The introduction of magnetic property in the nanocomposite state of the sample containing the ligand, 2-BOP may be quite interesting for applications in different bio-medical fields [10,20] Materials and methods Nanocomposite samples of CuCl2$2H2O-2-BOP are synthesized by the chemical method using CuCl2$2H2O and 2-BOP as precursor materials To prepare the sample we have consulted different methods adopted earlier [15,16,20,21] and a modified method has been considered and applied to synthesize the samples 2-BOP, with purity grade 98%, was purchased from Aldrich chemical company, USA and was used after checking its purity by HPLC CuCl2$2H2O, with purity grade 99%, was purchased from Merck India Spectroscopic grade methanol was purchased from S.L.R, India and used as such First of all, 20 ml of methanol was taken in a beaker and the required amount of CuCl2$2H2O (0.40 gm, 2.37 m mol) was added to prepare the solution of CuCl2$2H2O in it In another beaker, the required amount of 2-BOP (1.610 gm, 8.82 m mol) was taken and 20 ml methanol was added drop wise to prepare the 2-BOP solution To get homogeneity, both the solutions were stirred for about 15 at room temperature (RT) After the completion of stirring, the solution of the organic ligand (2-BOP) was added drop wise to the salt solution at RT and the rigorous stirring condition of the salt solution was maintained during the addition of the ligand solution The color of this solution was light green Then the homogeneous mixture of the two solutions was covered with a paraffin film and several tiny pours were created on the film for slow evaporation The beaker containing the final solution was kept inside a larger beaker containing silica gel and this beaker was also covered by the porous paraffin film Finally, this homogeneous mixture of the two solutions was left for slow evaporation After two weeks, small powder like tiny crystals of the compound were collected after washing in methanol, dried under vacuum at 40 C and used for investigation Experimental X-ray diffraction patterns of the individual component (CuCl2$2H2O and 2-BOP) and the nanocomposite were recorded by Brukers Advanced D8 diffractometer with Cu Kf radiation (l ¼ 0.15425 nm) in the range of 2q from 10 to 80 FESEM observations were carried out by using a FEI Inspect-F50 scanning electron microscope TEM micrograph was obtained using a JEOL JEM 1400 Plus (120 KV) electron microscope Raman spectra of the samples were recorded with J.Y HORIBA, T 64000 system RAMAN Spectrophotometer interfaced with a computer in the photon counting mode and tted with an Arỵ ion laser using 514.5 and 488.0 nm as exciting wavelengths FTIR spectra of the compound were recorded by PerkineElmer Model 783 spectrophotometer Static magnetic susceptibility of the sample was measured in the temperature range 14e300 K using a sensitive Faraday magnetometer fabricated in our Laboratory [23,24] The low temperature environment in the magnetic measuring set up was generated by a closed cycle helium cryo-cooler of APD cryogenics All the measuring instruments were interfaced with a computer and the measurements were carried out at different low temperatures with special reference to the temperature calibration of the sample chamber To measure the magnetic susceptibility, a small plastic packet containing the sample was suspended by a thin quartz fiber in a region of constant vertical magnetic field gradient [i.e., Hz (dHz/ dx) is constant] Diamagnetic correction for the suspension system including the empty plastic packet was duly considered in the calculation of the susceptibility 3.1 X-Ray Diffraction analysis An X-ray diffraction (XRD) pattern of the nanocomposite sample is shown in Fig 1(c) To confirm the formation and also to distinguish the crystallographic phase of the synthesized nanocomposite sample of 2BOP-CuCl2$2H2O from those of the individual components, we have also recorded the X-ray diffraction patterns of 2BOP and CuCl2$2H2O, and the corresponding patterns are shown in Fig 1(a) and (b), respectively The X-ray diffraction pattern of 2-BOP was taken as the standard pattern for the preparation of the nanocomposite sample of CuCl2$2H2O-2-BOP To substantiate this fact we have also consulted the available JCPDS file (No 13-0717) in this family of compounds Results show that almost all peaks (except very few) are matched well with the observed peaks shown in Fig 1(a) All the peaks in the XRD pattern of Fig 1(b) are matched very well with those of the desired phase of CuCl2$2H2O and the peaks are assigned by using the JCPDS file (No 33-0451) Interestingly, all the peaks of CuCl2$2H2O and 2-BOP are also developed in this pattern According to the JCPDS file No of 13e0717 for CuCl2$2H2O it is seen that the strongest peak of CuCl2$2H2O is found at̴ 16.22 This peak is also developed in the XRD pattern of the composite sample marked as symbol ♯ (Fig 1) Actually this peak is the superposition of two peaks corresponding to CuCl2$2H2O and 2-BOP The peak for the nanocomposite is slightly shifted which is quite likely due to the mismatch of the crystal structures of CuCl2$2H2O and 2-BOP Normally, strain is developed due to this mismatch which leads to the shift of the peak compared to its position in the pristine state Similarly, other peaks of CuCl2$2H2O (at̴ 44.74 and̴ 68.62 ) are also developed in the composite sample (indicated by ♯ in Fig 1) The crystalline structure of CuCl2$2H2O, thus, is retained in the composite sample There is a superposition of the peak of CuCl2$2H2O around 44 with a peak of 2-BOP as shown in Fig indicated by the symbol ♯ The peak of CuCl2$2H2O at around 68 is not visible in the XRD pattern of the composite because of the dominantly high intensity of the other peaks in the pattern This peak is present in the composite sample pattern which is shown in the inset of Fig This fact confirmed the Fig X-ray diffraction patterns of (a) 2-benzoylpyridine (2-BOP), (b) copper chloride (CuCl2$2H2O) and (c) copper chloride-2-benzoylpyridine nanocomposite sample (Cue2BOP) S Datta et al / Journal of Science: Advanced Materials and Devices (2018) 113e121 presence of each individual phase in the composite sample It should be mentioned here that in the XRD pattern of the composite sample (Fig 1(c)) some peaks of the CuCl2$2H2O and the ligand (2BOP) are shifted with reference to those of their individual pattern These slight shifts are attributed to the fact that the lattice strain has developed in the composite state causing the positions of these peaks to change No additional peak is found in the nanocomposite state and this confirms the formation of the desired composite phase The average crystallite size of each component of the composite was also calculated from the broadening of the most intense peaks in the pattern of Fig 1(c) using the DebyeeScherrer equation, D ẳ 0:89l=b1=2 cos qị Here 〈D〉 is the average crystallite diameter, l is the wavelength of the incident X-ray radiation and q is the corresponding Braggs angle, b1/2 is the full width at half maximum (FWHM) of the most intense peak The average size of crystallites of the composite is ~68 nm We have estimated the average crystallite size of CuCl2$2H2O and 2-BOP in the composite using the broadening of the most intense peaks of the respective individual components The crystallite sizes of CuCl2$2H2O and 2-BOP in the composite are 77 nm and 58 nm, respectively The crystallite size of the CuCl2$2H2O and 2-BOP components in the pure individual form are 90 nm and 20 nm, respectively The formation of the nanocrystalline composite has been confirmed by the estimated size obtained from the XRD pattern The uncertainty in the determination of crystallite size was estimated from the error in the fitting procedure and it lies within the range ±1 nm The estimated values of the crystallite size differ largely from the respective values of the individual components This difference is attributed to the fact that in the composite phase, there may exist a strain due to the presence of two different phases of CuCl2$2H2O and 2-BOP Owing to this fact the estimation of the crystallite size by DebyeeScherrer equation may not be justified since the broadening of each peak in the XRD pattern is not only due to the size of the nanocrystallite but also due to the lattice strain, apart from the inherent instrumental broadening For this, we have considered the HalleWilliamson (HeW) method for the estimation of the average particle size and the lattice strain of the sample [25,26] The required equation in the HeW plot is bcosq ẳ l/D ỵ 2sinq, where D is the average particle size, b is the full width at half maximum (FWHM) after the instrumental broadening correction, K is a constant (¼ 0.89), l is the wavelength, q is the Bragg angle, and ε is the lattice strain introduced inside the sample bcosq is plotted as a function of 2sinq, which normally gives a straight line The fitting is quite satisfactory which indicates the existence of lattice strain in the composite sample The strain is obtained from the slope of the line and the average particle size is also determined from the ordinate intercept Fig Plot of b cosq vs sinq (HalleWilliamson plot) of the nanocomposite sample 115 (see Fig 2) The calculated particle size is 105 nm and the strain in the nanocomposite CuCl2$2H2O-2-BOP is 27.5 Â 10À4, which arises mainly due to the mismatch of crystal structures of the two components in the composite This strain also has some influence on the Raman spectra of the nanocomposite, which will be discussed in the section of Raman and infrared spectra 3.2 FESEM analysis The morphology of the composite sample has been observed in FESEM micrographs shown in Fig where two selected micrographs recorded during the SEM observations are displayed (see 3a and 3b) The particles in Fig 3(a) and (b) are mostly spherical but bigger size particles of different shapes are also seen in the micrographs Most of the particles have an average diameter of 105 nm which is in agreement with the crystallite size obtained from the HeW plot To check the presence of the elements and also, to estimate the chemical composition of the compound, EDAX data of the nanocomposite sample has been recorded The corresponding results are shown in Fig 3(c) The EDAX measurement shows that the weight percentage of Cu and 2-BOP in CuCl2$2H2O-2-BOP are 27.95% and 72.05%, respectively and this is quite close with our chosen stoichiometry of the precursors used for the preparation of the sample 3.3 TEM analysis The observed TEM micrograph is shown in Fig 4(a) The nanostructure of the particles is clearly evidenced in the micrograph Nanoparticles are more-or-less spherical in shape The measured size of nanoparticles varies from 20 to 120 nm As shown by the particle size distribution in Fig 4(b), the size of most of the particles lie in the range between 40 and 70 nm The particle size distribution in Fig 4(b) is well fitted by the log normal function which is usual for nanoparticles system The weighted average size obtained from the distribution graph is ~75 nm 3.4 Molecular geometry The detailed structural view of the composite was achieved by ab initio DFT calculations Using the Gaussian 03 program package, the theoretical calculations were performed by density functional level of theory (DFT) using unrestricted B3LYP [i.e Becke three hybrid exchange and LeeeYangeParr correlation functional program (LYP)] The calculations of the system containing C, H, N, O and Cl centers were described by the standard Pople split valance polarization basis set 6e31ỵG(d,p), while for Cu2ỵ ion the LanL2DZ was used By allowing relaxation of all the parameters a realistic optimized structure was obtained which corresponds to the true energy minimum This optimized structure is shown in Fig and some selected values of the parameters of this structure are shown in Table The structural parameters calculated theoretically, were compared with those obtained from the similar type of studies of the ligand Bond lengths and bond angles of the phenyl and pyridyl rings are in good agreement with those found in the structure of the ligand 2-BOP [22] The structural features of the inner sphere of the metal ion point towards a distorted octahedral symmetry of the composite with the two chlorine atoms lying on the axial line The angle between the two ring planes of the ligand in the composite is about 43 which can be compared with 60 in the free ligand [22] The two rings are found slightly distorted and increased in size in the nanocomposite However, as in the case of the carbonyl group, its planarity is maintained Another interesting thing is that the length of the CCx bonds (between carbonyl carbon and its nearest pyridyl/phenyl ring carbon) 116 S Datta et al / Journal of Science: Advanced Materials and Devices (2018) 113e121 Fig SEM image of the nanocomposite sample Cu-2-BOP in (a) mm, (b) 10 mm scale and (c) Energy dispersive X-ray (EDX) spectra of Cu-2-BOP Fig TEM image: (a) micrograph and (b) histogram of particle size distribution is small in comparison to the corresponding entities of the free ligand In addition to this it is also noticed that the C]O bond length is larger in the composite (1.283 Å) than that of the free ligand (1.213 Å) The increase in the carbonyl (C]O) and the decrease in the Ccarbonyl À CC/N (ligand) bond lengths are compatible with the observed interesting spectral features, which will be discussed below in the Raman/infrared spectra of the composite 3.5 Magnetic properties To investigate the magnetic behavior of the nanocomposite sample of CuCl2$2H2O-2-BOP and also to estimate the valency of the Cu-cation in the compound, the magnetic susceptibility was measured in the temperature range of 14e300 K To know the modulation of the magnetic cation behavior in the presence of the organic ligand in the composite, the magnetic susceptibility of 2BOP was also measured The measured value of the molar susceptibility of 2-BOP confirms its diamagnetic nature But the magnetic susceptibility of the composite is found to be much higher than that of 2-BOP The measured value of the susceptibility at RT with an applied field 1000 Gauss is 1.82 Â 10À6 emu/g This observation clearly proves that the magnetic contribution of the compound arises mainly due to the copper chloride part whose magnetic moment arises from the incomplete shell of the Cu-ions The S Datta et al / Journal of Science: Advanced Materials and Devices (2018) 113e121 117 the compound is shown in Fig 6, which shows that the magnetization increases slowly with the lowering temperature To know the magnetic state and its transition, if any, in the measured temperature range (14e300 K) of the compound, we have tried to fit the observed susceptibility vs temperature curve by the CurieeWeiss law, c ¼ C/(T À q), where C is the Curie constant and q is the Curie temperature It is evident from Fig that the susceptibility increases with lowering the temperature and the CurieeWeiss law successfully fits the observed variation of the susceptibility measured in the range of 14e300 K This in turn also indicates that the sample is paramagnetic in the entire investigated range of temperature The values of C and q estimated from the CurieeWeiss fitting are 0.00078 emu K/mole and À1.2156 K, respectively This negative value of q is mainly due to the crystal field effect which is also found in different cases of our earlier studies [23,24] rather than any antiferromagnetic effect The thermal variations of the inverse susceptibility (1/c ¼ H/M) of the nanocomposite sample is also displayed in the inset of Fig The linear fitting suggests that the sample exhibits paramagnetic behavior in the entire measured range of temperature (14e300 K) 3.6 Raman and infrared spectra Fig Optimized structural view, obtained from ab initio DFT calculation, of CuCl2-2benzoyl pyridine (Cu-2-BOP) nanocomposite average value of the magnetic moment of the compound has been estimated from the average molar susceptibility using the formula Peff ¼ 2.828 (cM T)0.5, (where cM being the average molar susceptibility) and the magnetic moment thus found at RT is as large as 1.923 mB We have calculated the theoretical value of the magnetic p moment of the Cuỵ2 ion from the equation 4SS ỵ 1ị and the corresponding calculated value is 1.732 mB [27] In this calculation we did not consider the contribution of the orbital angular momentum which is normally quenched by the crystal field acting on the 3d-ion in the crystalline environment of diamagnetic neighbors Thus the measured value of the magnetic moment of the sample, obtained from the measured value of the susceptibility at RT, is higher than the corresponding theoretical value The higher value of the magnetic moment of the sample suggests that the crystal field effect of the Cu-ions is less in the composite compared to that of CuCl2$2H2O, where the orbital momentum contribution is almost nil due to the quenching effect In the present nanocomposite, the magnetic ion in the salt is coordinated to the organic molecule, 2-BOP and the higher magnetic moment indicates incomplete quenching of the orbital moments Due to this incomplete quenching, the magnetic moment gets some contribution from the orbital part This fact of incomplete quenching is also correlated with the formation of the nanocrystallite of CuCl2$2H2O in the nanocomposite phase which is not the case in the bulk phase Here the ground state (2D) of the Cu2ỵ ion would split into one triplet and one doublet states, where the distribution of different levels in the triplet will depend on the strength of the crystal field The ground state of the ion has two fold spin degeneracy and five fold orbital degeneracy In fact, this will further split the degenerated levels and consequently the population will be redistributed The ions will be populated among these levels according to Maxwell-Boltzmann law and the susceptibility can be calculated from the Van-Vleck expression, which will give the proper value of the magnetic moment The present value suggests that most of the Cu2ỵ ions are populated in the higher states among the crystal field levels Due to this fact the free ion magnetic moment is modified, where different crystal field levels contribute to the magnetic moment according to their population The thermal variation of magnetization recorded under zero field conditions of In order to get structural information of the composite sample, to verify the valence state of the metal ion and also to get insight into the effect of coordination on the ligand, we have thoroughly examined the vibrational spectra (both Raman and infrared) of the sample For comparison, the Raman spectra of the sample and the pure ligand (2-BOP) are both recorded under identical conditions for exciting wavelengths lexc ¼ 515.5 and 488.0 nm and they are shown in Figs and 8, respectively The measured infrared spectrum was analyzed and the obtained results are shown in Table Some interesting changes are noted in the Raman spectra of the sample when compared with those of the pure ligand It is worth mentioning that the composite exhibits an overall reduction of intensity of the Raman bands with respect to the free ligand Moreover that the composite exhibits not only an overall reduction of intensity of the Raman bands, but some changes in the relative intensities of the bands have also been observed compared with the free ligand The C]O stretching frequency has revealed a downshift from 1665 cmÀ1 in the free ligand to about 1650 cmÀ1 in the sample indicating the coordination of the metal with both oxygen and nitrogen atoms of the ligands [21] Some new bands are found to appear in the lower frequency region (below 500 cm À1) of the Raman spectra of the composite (Figs and 8), which signify the coordination of the divalent metal (Cu2ỵ) ions with the nitrogen and oxygen atoms and also with the two chlorine atoms The two weak Raman bands at 242 and 265 cm À1 have been assigned to the CueCl stretching vibrations [26] Two new Raman bands, appearing in the sample at 317 and 393 cmÀ1 are assigned to the two CueO stretching vibrations in accordance with the previous works [28,29] Another weak but prominent IR bands is observed at 498 cmÀ1 This band along with another equally weak infrared band at 517 cmÀ1 (having a weak Raman counterpart at 520 cmÀ1) have been assigned to two CueN stretching vibrations [29] Interestingly these two bands are absent in the infrared spectra of the free ligand Four Raman bands, observed around 989, 1001, 1026 and 1053 cmÀ1, are respectively correlated with the angle bending, a (CCC/CNC/CCN), a (CCC), d (CH) and ring stretching, n (CC/CN) modes of the two rings This group shows an overall reduction in intensity relative to the n (C]O) mode in the compound when compared with the free ligand Besides this, the intensity of the second band is reduced so significantly that the relative intensities of the second and the third bands are found to be reversed in the sample with respect to those of the free ligand Moreover, the first 118 S Datta et al / Journal of Science: Advanced Materials and Devices (2018) 113e121 Table Equilibrium geometry of CuCl2-2-BOP (A) Bond lengths and bond angles in the geometry formed by copper ion with O, N and Cl atoms Bond lengths in Å RCoO R(Cu47eO22) 2.021 RCoN R(Cu47eN23) 1.995 RCoCl R(Cu47eCl49) 2.473 Bond angles in degrees A(O22Cu47N23) 81.01 AOCoN AOCoN A(O37Cu47N23) 98.99 AClCoCl A(Cl48Cu47Cl49) 180.00 ANCoN A(N23Cu47N39) 178.62 AOCoO A(O22Cu47O37) 179.09 ANCoCl A(N23Cu47Cl49) 90.69 ANCoCl A(N39Cu47Cl49) 90.68 AOCoCl A(O22Cu47Cl49) 89.54 AOCoCl A(O37Cu47Cl49) 89.54 (B) Selected bond lengths and bond angles of the ligand Bond lengths in Å RCC/CN Ring I Cu-2-BOP complex 1.369 R(N23eC2) R(C2eC3) 1.404 R(C3eC5) 1.410 R(C5eC7) 1.404 R(C7eC4) 1.410 R(C4eN23) 1.344 RCC R(C2eC1) 1.493 Bond angles in degrees ACCC/CCN/CNC Ring I Cu-2-BOP complex A(N23C4C7) 120.69 A(C4C7C5) 118.99 A(C7C5C3) 119.54 A(C5C3C2) 118.82 A(C3C2N23) 120.38 ACCX A(N23C2C1) 113.26 A(C3C2C1) 126.22 R(Cu47eO37) R(Cu47eN39) R(Cu49eCl48) 2.021 1.995 2.480 A(O37Cu47N39) A(O22Cu47N39) 81.01 98.99 A(N23Cu47Cl48) A(N39Cu47Cl48) A(O22Cu47Cl48) A(O37Cu47Cl48) 89.30 89.31 90.45 90.45 2-BOP (1.333) (1.395) (1.390) (1.392) (1.398) (1.339) (1.517) Ring II Cu-2-BOP complex R(C11eC12) R(C13eC11) R(C16eC13) R(C18eC16) R(C14eC18) R(C12eC14) R(C11eC1) 1.420 1.420 1.402 1.410 1.411 1.401 1.467 2-BOP (1.402) (1.401) (1.393) (1.393) (1.396) (1.388) (1.498) 2-BOP (123.69 ) (118.30 ) (118.67 ) (118.64 ) (123.98 ) (115.67 ) (121.18 ) Ring II Cu-2-BOP complex A(C12C14C18) A(C14C18C16) A(C18C16C13) A(C16C13C11) A(C13C11C12) A(C12C11C1) A(C13C11C1) 119.990 120.230 120.160 119.810 119.710 118.250 121.930 2-BOP (120.01 ) (120.01 ) (120.04 ) (120.31 ) (119.19 ) (117.99 ) (122.76 ) (C) Bond lengths and bond angles of the carbonyl group Bond lengths in Å RCO Bond angles in degrees R(C1eO22) Cu-2-BOP complex 1.283 2-BOP (1.213) ACXC ACCO ACCO A(C2C1C11) A(C2C1O22) A(C11C1O22) Cu-2-BOP complex 124.300 116.220 119.460 2-BOP 119.40 119.26 121.34 one exhibits a red shift along with a significant reduction in intensity and the last one a blue shift in the composite Similar observations were evidenced in the case of the two bands at 1165 and 1177 cmÀ1 Of these, the first one in the sample exhibits an increase in the relative intensity Another weak Raman band around Fig Thermal variation of the molar susceptibility of the nanocomposite sample Cue2BOP The thermal variations of the inverse susceptibility (1/c ¼ H/M) of the nanocomposite sample is shown in the inset Fig Raman spectra of (a) 2-BOP, (b) Cue2BOP nanocomposite (for lexc ¼ 514.5 nm) The spectrum in the region between 100 and 600 cmÀ1 is shown in the inset S Datta et al / Journal of Science: Advanced Materials and Devices (2018) 113e121 119 1095 cmÀ1 in the free ligand 2-BOP becomes much enhanced in the compound and shows an upshift of about 20 cmÀ1 (to around 1115 cmÀ1) Although this mode is bCH (I) (angle bending mode of ring I), there is also a good contribution of the stretching vibrations to this mode [22] This indicates that the ring (I) bond which is the main contributor to the potential energy distribution of this vibration is significantly contracted Three ring stretching n (CC) modes are observed in the free ligand in the region between 1560 and 1600 cmÀ1 Interestingly, the relative intensity of the third vibration (around 1596 cmÀ1) with respect to the n (C]O) mode is found to increase largely in the composite Three low frequency Raman bands are observed at 129, 137 and 178 cmÀ1, of which the last one is very weak These modes are assigned to the metal centered angle bending modes as already reported [30e32] Drastic change of intensities of some of the Raman bands of both the rings, for example, enhancement of the CH-bending mode of the pyridyl ring (I) at 1113 cmÀ1 and phenyl ring modes at 1026, 1165 and Fig Raman spectra of (a) 2-BOP, (b) Cue2BOP nanocomposite (for lexc ¼ 488.0 nm) The spectrum in the region between 100 and 600 cmÀ1 is shown in the inset Table Raman and infrared spectra (cmÀ1) of 2-benzoylpyridine (2-BOP) and copper chloride-2-benzoylpyridine nanocomposite sample (Cu-2-BOP) Excitation wavelength 514.4 nm 2-BOP Int 155 506 211 231 320 134 286 360 355 30 400 400 431 446 420 420 273 60 Excitation wavelength 488.0 nm Cu-2-BOP Int 2-BOP Int 129 137 (sh) 165 178 197 228 241 265 292 317 352 364 393 402 411 439 454 496 517 96 15 41 88 39 12 15 4 12 21 13 10 10 10 157 203 214 232 285 44 355 432 152 FTIR Int 131 138 (sh) 165 178 197 229 242 sh 265 289 317 350 362 393 404 415 437 (vw) 457 32 11 30 112 9 10 8 27 10 401 (s) 431 (m) 446 (m) 45 574 (m) 574 430 570 40 575 102 521 550 571 614 650 363 235 614 648 32 12 617 652 102 88 614 646 42 11 731 750 775 936 250 344 731 758 40 29 733 437 778 255 731 762 778 50 43 10 855 210 (927) (w) 919 20 994 1001 1029 1048 1090 1161 1169 (1241) (1269) 1282 1303 (1416) (1450) (1465) 1568 1587 1596 1664 1424 2912 1064 747 35 (w) 581 1796 989 vw 1001 1026 1053 1113 1165 1177 1249 1263 sh 1292 74 99 43 32 68 69 20 14 919 949 987 1002 1027 1055 1115 1165 1179 1251 1263 1292 1317 26 40 15 132 163 72 53 134 138 27 28 21 20 1447 1479 1570 18 27 56 1450 1480 1571 22 50 165 1598 1649 122 135 1598 1650 480 515 248 195 354 1001 630 2665 995 1002 1032 1050 1095 1162 1171 (1241) (1269) 1284 (1416) (1450) (1465) 1568 1588 bsh 1600 1666 507 1404 463 463 30 299 476 50 98 120 295 613 Assignments Cu-2-BOP 2-BOP 614 (s) 650 (vvs) 688 (s) 731 (vs) 750 (vs) 777 (vs) 818 (s) 856 (m) 876 (vvw) 925 (s) 943 (vs) 992 (s) 1000 (sh) 1026 (m) 1047 (m) 1090 (m) 1159 (vs) 1168 (s) 1241 (s) 1282 (vs) 1316 (vvs) 1448 1466 1567 1585 1592 1668 (vs) (s) (m) (m) (m) (vvs) Cu-2-BOP 416 (wm) 437 (m) 460 (m) 498 (w) 517 (w) 551 (vwsh) 574 (w) 600 (vwsh) 619 (m) 650 (vs) 692 (vs) 728 (m) 759 (s) 779 (s) 821 (s) 848 (m) 875 (vw) 919 (w) 948 (vs) 977 (m) 1001 (m) 1027 (s) 1055 (m) 1113 (s) 1156 (m) 1173 (vs) 1250 (vs) 1286 1318 1400 1443 1473 1572 (m) (vs) (wm) (vs) (vvw) (s) 1594 (vs) 1646 (vvs) OeCueN angle bend OeCueN angle bend CCx wag NeCueN angle bend CCx bend(I) CCx bend (II) CueCl stretch CueCl stretch CCX sym Stretch CueO stretch CXeO bend 165 ỵ 197 CueO stretch Ring torsion(I) Ring torsion (II) Ring torsion(I) Ring torsion (II) CueN stretch CueN stretch 229 ỵ 317 CCXC bending 165 ỵ 437 CCC ring bending(I) CCC ring bending (II) Ring torsion (II) CCC ring bending(I) Ring torsion(I) CH wag(I) CxO wag CH wag (II) 416 ỵ 460 CC stretch (II) CH wag (II) CCC ring bending(I) CCC ring bending (II) CH bending (II) CC/CN stretch(I) CH bending(I) CH bending (II) CH bending (II) CCX asymmetric stretch CC/CN stretch(I) CH bending(I) CC stretching (II) CC/CN stretch(I) CC/CN stretch(I) CC stretch (II) CC/CN stretch(I) CC/CN stretch(I) CC stretch (II) CXO stretch (bracketed wave numbers) e taken from Ref 22 Cx corresponds to the carbon atom belonging to the carbonyl group IR intensities are accordingly abbreviated 120 S Datta et al / Journal of Science: Advanced Materials and Devices (2018) 113e121 1598 cmÀ1 and reduction in intensity of the CCC angle bending mode of the pyridyl ring (I) at 994 cmÀ1, indicate that coordination of the metal ion [Cu2ỵ] modies the charge distribution of the two rings in conformity with the change of the intensity pattern It also generates both upward and downward frequency shifts both in the infrared and Raman spectra of the composite with respect to the free ligand of an amount in the range of 0e20 cmÀ1 All these things indicate the coordination with the nitrogen and oxygen atoms and the back donation from the metal ion to the anti bonding orbital of C]O The latter not only increases the C]O bond lengths and decreases the carbonyl stretching wavenumber but also modifies the charge distribution of the CCx (i.e CxCrings) bonds resulting in the upshifts of the CxCrings stretching wavenumbers in the composite (see Table 2) The shifts and intensity changes of the Raman bands in the composite compared to those of their individual components are also in agreement with the developed strain obtained from the HeW plot Thus from the spectral characteristics and the presence of the metal e oxygen/nitrogen/chlorine stretching vibrations, two each, a distorted octahedral structure is expected in conformity with the previous observations made by Plytzanopoulous et al [21] and also compatible with the structure shown in Table Conclusion Composite samples of CuCl2$2H2O-2-BOP with desired crystallographic phase have been successfully prepared by the chemical method The nanocrystallite size of the individual components is found not calculated by the DebyeeScherrer method due to the strain developed in the nanocomposite The strain developed due to the mismatch of the crystal structure of the two constituting components and the crystallite size of the nanocomposite was estimated from the HeW plot The nanocrystallite size cannot be calculated by the DebyeeScherrer method However, it is quite reliable and comparable with that obtained from FESEM and TEM micrographs This observation also suggests that most of the particles displayed in the micrographs are single crystallites, but not clusters of nanocrystallites Interestingly, the magnetic property of 2-BOP has been enhanced thanks to the combination with the relatively strong magnetic part of CuCl2$2H2O through the formation of the composite system The composite system exhibits a paramagnetic behavior in the range of 14e300 K This paramagnetic behavior would be useful for applications, where substantial magnetic moment is needed In addition, the magnetic property may be fruitful for different biomedical fields, where positive and relatively high value of magnetic moment of 2-BOP is required The observed value of magnetic moment is high compared to that of the free ion magnetic moment, where orbital contribution is not fully quenched in the crystal field of the organic environment The departure is attributed to the redistribution of Cu2ỵ ion in different crystal field levels, where the magnetic moment mainly gets its contribution from the high spin state according as the population determined by Boltzmann 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behavior in the range of 14e300 K This paramagnetic behavior would... compound, the magnetic susceptibility was measured in the temperature range of 14e300 K To know the modulation of the magnetic cation behavior in the presence of the organic ligand in the composite, the