The title compound, 1-4-(dimethylamino)benzylidene)-4-(naphthalene-1-yl) thiosemicarbazide (DMABNTS, C20H20N4S, M-r = 348.47), was synthesized and characterized by elemental analysis, IR, H-1 NMR and MS. The crystal structure of DMABNTS with 1,4-dioxane (Diox, C4H8O2) solvent molecules (DMABNTS(.)2Diox, C28H36N4O4S, M-r = 524.67) was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic system, space group P2(1)/c with a = 14.418(4), b = 7.1702(19), c = 28.350(7) angstrom, beta = 101.154(6)degrees, V = 2875.4(13) angstrom(3), Z = 4, D-c = 1.212 g/cm, F(000) = 1120 and mu = 0.151 mm(-1). A total of 6458 reflections were collected, of which 4671 were unique. The structure was solved by direct methods and refined to the final R = 0.0732 and wR = 0.2127 for 3921 observed reflections (I > 2 sigma(I)). There exist intermolecular hydrogen bonds (N(2)-H(2B)center dot center dot center dot S(1A) and N(1)-H(1A)center dot center dot center dot O(4B)) in the structure. The study of fluorescent properties shows that DMABNTS emits bright solid-state fluorescence in the visible region and exhibits blue photoluminescence

Huang Rong-Bin

Lin Li-Rong

Yu Yun

林丽榕

黄荣彬

Xiamen University Institutional Repository

25卷 10期                           结  构  化  学（JIEGOU HUAXUE）                    Vol. 25,  No. 10 2006. 10                               Chinese  J.  Struct. Chem.                                 1197~1202  Synthesis, Crystal Structure and Fluorescent  Properties of 1-(4-(Dimethylamino)benzylidene)- 4-(naphthalen-1-yl) Thiosemicarbazide①  YU Yuna  LIN Li-Rongb① HUANG Rong-Binb  a (Department of Chemistry, Longyan College, Longyan, Fujian 364000, China) b (Department of Chemistry, Xiamen University, Xiamen 361005, China)  ABSTRACT  The title compound, 1-4-(dimethylamino)benzylidene)-4-(naphthalene-1-yl) thiose- micarbazide (DMABNTS, C20H20N4S, Mr = 348.47), was synthesized and characterized by elemental analysis, IR, 1H NMR and MS. The crystal structure of DMABNTS with 1,4-dioxane (Diox, C4H8O2) solvent molecules (DMABNTS·2Diox, C28H36N4O4S, Mr = 524.67) was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic system, space group P21/c with a = 14.418(4), b = 7.1702(19), c = 28.350(7) Å, β = 101.154(6)°, V = 2875.4(13) Å3, Z = 4, Dc = 1.212 g/cm3, F(000) = 1120 and µ = 0.151 mm−1. A total of 6458 reflections were collected, of which 4671 were unique. The structure was solved by direct methods and refined to the final R = 0.0732 and wR = 0.2127 for 3921 observed reflections (I > 2σ(I)). There exist intermolecular hydrogen bonds (N(2)–H(2B)⋯S(1A) and N(1)–H(1A)⋯O(4B)) in the structure. The study of fluorescent properties shows that DMABNTS emits bright solid-state fluorescence in the visible region and exhibits blue photoluminescence. Keywords: 1-(4-(dimethylamino)benzylidene)-4-(naphthalen-1-yl)thiosemicarbazide,  synthesis, crystal structure, fluorescence  1  INTRODUCTION  Recently, for the fluorescent properties, Schiff base has been more and more important and widely studied in density optical memories, nonlinear op- tics (NLO), organic light-emitting diodes (OLED), polymer LED and electrogenerated chemilumines- cence (ECL)[1~5]. Thiosemicarbazones are a kind of Schiff bases with thiourea and good ligands easily chelating with transition metal ions. Although they have been studied extensively for a long time due to their chemical and biological activities, such as antitumor, antibacterial and antiviral[6～8], there are only few reports concerning the solid fluorescent properties of thiosemicarbazones[9]. It is interesting to design and synthesize new thiosemicarbazone de- rivatives with solid fluorescence properties for the possible applications in these areas. Herein, we report the crystal structure of a new derivative of thiosemicarbazone containing electron donor substi- tute dimethylanilino, DMABNTS with 1.4-dioxane solvent molecules (DMABNTS·2Diox) and its fluo- rescence properties in different solvents as well as in solid state. Introduction of such a strong electron- donating moiety as N,N-dimethylanilino group through a double bond imparts new properties that are uncommonly observed for the parent thiourea to the resultant molecule. DMABNTS shows absorp-                                                                           Received 9 February 2006; accepted 26 April 2006 (CCDC 621111) ① Corresponding author.     Yu Yun, female, born in 1957, associate professor, majoring in inorganic chemistry. E-mail: yuyunshen@hotmail.com YU Y. et al.: Synthesis, Crystal Structure and Fluorescent Properties  1198                 of 1-(4-(Dimethylamino)benzylidene)-4(naphthalen-1-yl) Thiosemicarbazide               No. 10  tion in the near-visible region and emission totally in the visible region with bright solid-state fluores- cence. DMABNTS exhibits blue photolumines- cence.  1 EXPERIMENTAL  2. 1  Materials and apparatus 1-Naphthyl isothiocyanate was purchased from ACROS and used as received. The other analytical grade chemicals and solvents were from commercial sources. Solvents were redistilled before use to preclude the fluorescence impurities. Elemental analyses for C, H and N were carried out with a CE instruments EA 1110 Elemental Analyzer. The infrared spectra were recorded on a Nicolet AVATAR FT-IR360 spectrometer by using the pressed KBr pellet. 1H NMR spectrum was measured on a Varian Unity 500MHZ with TMS as the internal standard. Melting point was determined with an X-4 melting point apparatus. Corrected fluorescence spectra were taken on a Hitachi F-4500 fluorescence spectrophotometer and absorption spec- tra were scanned on a Bekeman DU-7400 absorp- tion spectrophotometer. Quantum yields were deter- mined using quinine bisulphate as standard[10]. Solid- state fluorescence spectra were recorded with solid powder on a 1 cm quartz round plate with excita- tion and emission slits 2.5/2.5 nm. The excitation wavelength for DMABNTS was 350 nm. All experi- ments were conducted at room temperature of ca. 25 ℃. 2. 2  Synthesis and characterization The synthetic route for the title compound is shown in Scheme 1.         Scheme 1.  Synthesis route of the title compound DMABNTS  2. 2. 1  Preparation of 4-(naphthalen-1-yl) thiosemicarbazide   1-Naphthyl isothiocyanate (0.741 g, 4 mmol) was dissolved in 30 mL of ethanol, and the resulting solution was then slowly added to 50% hydrazine hydrate (1.00 g, 10 mmol) in ethanol (10 mL). The mixed solution was stirred at room temperature for 8 h, and the white solid was collected by filtration and recrystallized by ethanol. 2. 2. 2  Synthesis and characterization of  1-(4-(dimethylamino)benzylidene)-4- (naphthalen-1-yl) thiosemicarbazide 4-(Naphthalen-1-yl) thiosemicarbazide (0.434 g, 2 mmol) was dissolved in 20 mL of ethanol and added to a refluxing ethanol solution of 0.298 g (2 mmol) p-dimethylaminobenzaldehyde. The mixed solution was further refluxed for about 6 h, forming light yellow precipitate which was then filtered off under low pressure and washed several times with ethanol. The product was recrystallized from ethanol, and dried under vacuum for 4 h. Yield 0.362 g (52%). m. p: 210～211℃. Anal. Calcd. (%) for C20H20N4S: C, 68.94; H, 5.79; N, 16.08. Found (%): C, 69.08; H, 5.63; N, 15.95. IR (KBr): 3435.68, 3315.03 (NH, s); 3132.11, 2976.45 (CH3, m); 1614.27, 1520.86, 1497.51 (C = N, C = C, s); N C S+ 50%  N H 2N H 2.H 2OH NH NNH 2Saa +NCHONN NHNHS( DM ABNTS ) 2006  Vol. 25                结  构  化  学（JIEGOU HUAXUE）Chinese  J.  Struct.  Chem.               1199  1178.36 (C= S, s); 1H NMR (500MHZ, DMSO) δ: 2.969(s, 6H, CH3; 6.715～7.720 (d, 8H, H2, H4, H5, H8, H14, H15, H17, H18); 7.878～7.975(t, 3H, H3, H6, H7); 8.090(s, 1H, HC=N); 10.209(s, 1H, NH); 11.680(s, 1H, N-NH); MS m/z (%): 349.0 (M++ 1, 100).  2. 2. 3  X-ray crystallography analysis Crystals suitable for diffraction were obtained by recrystallizing the products from 1.4-dioxane at room temperature. A rectangular transparent crystal with dimensions of 0.52mm × 0.48mm × 0.42 mm was chosen and mounted at the top of a glass fiber in air. The diffraction data were collected on a Bruker Apex-2000 diffractometer equipped with a graphite-monochromatized MoKα (λ = 0.71073 Å) radiation by using an ω-φ scan mode at 173(2) K. A total of 6458 reflections were measured in the 2θ range (1.44≤2θ≤25.00º) and 4671 were inde- pendent with Rint = 0.0221, of which 3921 were con- sidered as observed (I > 2σ(I)). Lorentz-polariza- tion and empirical absorption corrections were applied to the data. The structure was solved by direct methods with SHELXS-97 and refined by full-matrix least-squares calculations with SHE- LXL-97 based on F2[11]. All non-hydrogen atoms were refined anisotropically and hydrogen atoms were located at the geometrically calculated posi- tions and rode on the related atoms. The final R = 0.0732, wR = 0.2127 (w = 1/[σ2(Fo2) + (0.1545P)2 + 1.9479P], where P = (Fo2 + 2Fc2)/3), S = 1.043, (∆/σ)max = 0.000, (∆ρ)max = 0.812 and (∆ρ)min = –0.424 e/Å3.  3  RESULTS AND DISCUSSION  3. 1  Crystal structure The 1H NMR, IR, MS and elemental analysis for the product are in good agreement with DMABNTS. The non-hydrogen atomic coordinates and equi- valent isotropic thermal parameters of DMAB- NTS·2Diox are listed in Table 1, and selected bond lengths and bond angles in Table 2. The single- crystal X-ray diffraction analysis exhibits that there are coordinating Diox solvent molecules in the crystal with the molar ratio of DMABNTS:Diox being 1:2. The crystal structure and intermolecular hydrogen bond diagram of the title compound are shown in Fig. 1.  Table 1.   Atomic Coordinates (× 104) and Equivalent Isotropic Displacement Parameters (Å2 × 103)  Atom x y z Ueq Atom x y z Ueq S(1) 4398(1) 7789(1) 382(1) 36(1) C(15) 3312(2) 7436(4) –2552(1) 32(1) N(1) 3411(2) 5946(3) –370(1) 30(1) C(16) 3734(2) 8663(4) –2836(1) 32(1) N(2) 4428(2) 8172(4) –537(1) 32(1) C(17) 4405(2) 9931(4) –2594(1) 34(1) N(3) 4102(2) 7847(3) –1018(1) 31(1) C(18) 4642(2) 9945(4) –2098(1) 35(1) N(4) 3503(2) 8632(4) –3328(1) 40(1) C(19) 3939(2) 9953(5) –3604(1) 46(1) C(1) 2922(2) 4885(4) –68(1) 29(1) C(20) 2873(2) 7247(5) –3579(1) 46(1) C(2) 3204(2) 3114(4) 60(1) 37(1) C(21) –1326(3) 9100(8) 2861(3) 107(2) C(3) 2718(2) 2044(5) 352(1) 45(1) C(22) –1958(3) 7705(7) 2975(2) 86(2) C(4) 1959(2) 2787(5) 507(1) 43(1) C(23) –750(3) 5528(7) 3060(2) 91(2) C(5) 860(2) 5413(6) 539(1) 51(1) C(24) –119(3) 6945(8) 2948(3) 103(2) C(6) 566(2) 7164(6) 407(2) 59(1) C(25) 2284(3) 3971(6) 3744(2) 79(1) C(7) 1028(2) 8203(6) 103(2) 55(1) C(26) 2890(3) 2533(6) 3590(2) 65(1) C(8) 1789(2) 7488(5) –55(1) 40(1) C(27) 1680(3) 371(6) 3539(2) 59(1) C(9) 2123(2) 5688(4) 80(1) 31(1) C(28) 1084(3) 1805(7) 3708(2) 72(1) C(10) 1645(2) 4607(5) 382(1) 37(1) O(1) –386(2) 8734(5) 3089(2) 133(2) C(11) 4046(2) 7258(4) –206(1) 28(1) O(2) –1688(2) 5918(4) 2841(1) 81(1) C(12) 4507(2) 8808(4) –1300(1) 31(1) O(3) 1311(2) 3607(4) 3561(1) 75(1) C(13) 4234(2) 8718(4) –1819(1) 30(1) O(4) 2644(2) 733(3) 3723(1) 48(1) C(14) 3554(2) 7463(4) –2059(1) 30(1)      Ueq is defined as one third of the trace of the orthogonalized Uij tensor.   YU Y. et al.: Synthesis, Crystal Structure and Fluorescent Properties  1200                 of 1-(4-(Dimethylamino)benzylidene)-4(naphthalen-1-yl) Thiosemicarbazide               No. 10  Table 2.  Selected Bond Lengths (Å) and Bond Angles (°)  Bond            Dist. Bond            Dist. Bond            Dist. S(1)–C(11)        1.691(3) N(2)–C(11)      1.344(3) N(4)–C(16)       1.371(3) N(1)–C(11)        1.332(4) N(2)–N(3)       1.375(3) N(4)–C(20)       1.438(4) N(1)–C(1)         1.429(3) N(3)–C(12)      1.277(4) N(4)–C(19)       1.447(4) Angle            (°) Angle             (°) Angle              (°) C(11)–N(1)–C(1)   123.5(2) C(16)–N(4)–C(19)   119.6(2) N(2)–C(11)–S(1)    119.5(2) C(11)–N(2)–N(3)   120.1(2) C(20)–N(4)–C(19)   118.9(2) N(3)–C(12)–C(13)   122.9(2) C(12)–N(3)–N(2)   114.8(2) N(1)–C(11)–N(2)    116.6(2)  C(16)–N(4)–C(20)  121.4(3) N(1)–C(11)–S(1)    123.9(2)                                                            Fig. 1.  Molecular structure and inter-                    Fig. 2.  Packing diagram of  molecular hydrogen bonds of DMABNTS                  DMABNTS·2Diox in a unit cell  The title compound molecule is composed of p-dimethylaminobenzyl, thiosemicarbazone and na- phthyl and has two planes. In p1, the phenyl ring does not show any unusual features and the bond lengths and bond angles are within the normal ranges[12]. The interatomic distance for C(12)–N(3) is 1.277(4) Å, showing it is a normal C=N double bond[13]. The sum of the bond angles S(1)–C(11)– N(1), S(1)–C(11)–N(2), N(1)–C(11)–N(2) and C(19)–  N(4)–C(16), C(20)–N(4)–C(16), C(20)–N(4)–C(19) is 360.0°, indicating the C(11) and N(4) atoms are of sp2 hybridization. The atoms C(11), C(12), C(19), C(20), N(1), N(2), N(3), N(4), S(1) and the phenyl ring (C(13)～C(18)) are coplanar (plane1) with plane equation 10.598x–4.861y–4.131z = 0.9348, and the mean deviation from the least-squares plane is 0.0486 Å. Furthermore, the atoms C(11), C(12), N(1), N(2), N(3), N(4), S(1) and the phenyl ring form a conjugated system so the C(11)–N(1) and C(11)–N(2) bonds (1.332 and 1.344 Å, respectively) are shorter than the normal C–N bond (1.47 Å)[14]. The C=S bond (1.691(3) Å) is slightly longer than the C=S double bond (1.646 Å)[15] and the bond distance of N(4)–C(16), 1.371 Å, is shorter than that of N(4)–C(19) and N(4)–C(20) (1.447 and 1.438 Å, respectively). In p2 (C(1)～C(10)), the bond lengths and bond angles are generally normal in the na- phthalene ring. The least-squares plane of the na- phthalene ring has the mean deviation of 0.0125 Å (plane 2 equation: 6.618x + 2.621y + 20.005z = 3.0534) and forms a dihedral angle of 85.0° between two planes. P-Dimethylaminophenyl at C(12) and 1-naphthyl thiourea at N(3) are located on opposite sides of the C(12)=N(3) double bond, so the com- pound is in a tras form. As shown in Fig. 1, in the title compound there exist intermolecular hydrogen bonding interactions of N(2)–H(2B)⋯S(1A)i  (i: –x+1, –y+2, –z) listed in Table 3. There are hydrogen bond acceptor and donor in every molecule, and a centrosymmetric dimer with an 8-membered ring is produced by the intermolecular hydrogen bonds.  Packing diagram of the molecule in a unit cell is shown in Fig. 2. The intermolecular hydrogen bond  2006  Vol. 25                结  构  化  学（JIEGOU HUAXUE）Chinese  J.  Struct.  Chem.               1201  400 450 500 5500200400600  Normalized intensity (a.u.)W avelengh / nmcHex, Diox, THF, EtOH, MeCN of N(1)–H(1A)⋯O(4B)ii (ii: x, –y+1/2, z–1/2) in the crystal has been observed between the title compound and 1.4-dioxane solvent molecules with O(4) from Diox and N(1) from DMABNTS. The hydrogen bond lengths and bond angles are listed in Table 3.   Table 3.  Hydrogen-bonding Geometry (Å and º)  Donor–H⋯accepter D–H H⋯A D⋯A D–H⋯A N(2)–H(2B)⋯S(1A) 0.88  2.53  3.341(3)  153.8 N(1)–H(1A)⋯O(4B) 0.88  2.05  2.859(3) 153.2 A: –x+1, –y+2, –z; B: x, –y+1/2, z–1/2    Table 4.  Solvatochromic Data of DMABNTS  Solvent (ε)a λmax Flu/nm [v/cm－1] ФFlu c λmaxabs /nm [v/cm－1] Stokes shift ∆vcm－1  εmaxb Diox (2.21) 419 [23866] 0.038 365 [27397] 3531 4.6 THF (7.58) 428 [23364] 0.016 369 [27100] 3736 4.8  EtOH (24.55) 443 [22573] 0.014 366 [27322] 4749 4.9 MeCN (37.50) 445 [22471] 0.015 364 [27472] 5001 4.9        a Dielectric constant (ε, from ref [16]) b Molar absorption coefficient (× 104 mol－1 l cm－1) c Fluorescence quantum yield, calculated using quinine bisulphate 350 nm as standard                                                           Fig. 3.  Normalized fluorescence spectra                   Fig. 4.  Fluorescence spectrum of of DMABNTS in different solvents                    DMABNTS in solid state excited                                             at 350 nm with excitation and                                              emission slits of 2.5/2.5nm  3. 2  Fluorescent properties of DMABNTS The UV-vis and fluorescence spectra of DMA- BNTS (1.29 × 10－5 M) in different solvents were recorded. The values of the spectra are listed in Table 4 and the fluorescence spectra are shown in Fig. 3. It can be seen that the π-π* transitions for DMABNTS appear close to the visible region. DMABNTS shows the longest wavelength absorp- tion maximum in near-visible region and emits blue fluorescence in different solvents, although its quantum yield is not high in all kinds of solvents. DMABNTS exhibits Stokes shift from 3531 cm－1 in Diox to 5001 cm－1 in MeCN, implying more pro- minent charge transfer in the excited state. The ab- sorption maxima recorded in various solvents reveal almost no shift from Diox to MeCN upon increasing the polarity of the solvent. There is a well-pro- nounced increase in the Stokes shift and decrease in emission quantum yield with the increase of polarity of the solvent. As shown in Fig. 3, the maximum of emission wavelength shifts from 419 nm in Diox to MeCN (445 nm) upon increasing the solvent polarity.  Bright emission of DMABNTS upon shining light 400 450 500 5500200400600800100012001400  Relative fluorescence intensityWavelength / nmYU Y. et al.: Synthesis, Crystal Structure and Fluorescent Properties  1202                 of 1-(4-(Dimethylamino)benzylidene)-4(naphthalen-1-yl) Thiosemicarbazide               No. 10  on solid sample is observed. The emission spectrum from solid powder is shown in Fig. 4. It can be seen from Figs. 3 and 4 that the solution fluorescence spectral maxima were almost the same with that of solid state. That the solid-state emission spectrum exhibits very close consistency with the solution fluorescence spectra indicates the solid emission from monomer. The characteristics are very useful in opening up new prospects and promises for novel organic materials, ECL, OLED, and other optoelec- tronic applications.  REFERENCES (1) Chai, H.; Liu, G. F.; Liu, L.; Jia, D. Spectrochimica Acta Part A–Molecular & Biomolecular Spectroscopy 2005, 61, 2590–2594. (2) Peng, B. H.; Liu, G. F.; Liu, L.; Jia, D. Z.; Yu, K. B. J. Photochem. & Photobio. A–Chem. 2005, 171, 243–249 (3) Liu, G. F.; Liu, L.; Jia, D. Z.; Yu, K. B. Struc. Chem. 2005, 16, 135–140.  (4) Wu, W. S.; Dai, J. C.; Zheng, Y. Y.; Huang, T. T; Lan, X. R.; Lin, Y. Y. Acta Chim. Sinica 2004, 62, 1801–1806. (5) Xue, Z. M.; Tian, Y. P.; Wang, D. J. Chem. Soc., Dalton Trans. 2003, 1373–1378.  (6) Bharti, N.; Shailendra; Sharma, S.; Naqvi, F.; Azam, A. Bioorg. & Med. Chem. 2003, 11, 2923–2929.  (7) Afrasiabi, Z.; Sinn, E.; Lin, W. 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Synthesis, crystal structure and fluorescent properties of 1-(4-(dimethylamino)benzylidene)4-(naphthalen-1-yl) thiosemicarbazide

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Synthesis, crystal structure and fluorescent properties of 1-(4-(dimethylamino)benzylidene)4-(naphthalen-1-yl) thiosemicarbazide

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