Materials and instruments
All the materials were acquired with a stated purity of 99% from Sigma-Aldrich Chemical and Merck Company and utilized without additional purification. On a PG Instruments T80 + UV/Vis spectrometer, the UV-Vis spectrums were recorded from a 1x10-3 M solution of the compounds in DMF, DMSO and DCM from 800 to 190 nm. The IR ATR spectrum was produced using the Attenuated Total Reflectance (ATR) model on a Perkin Elmer FT-IR spectrometer between 4000 - 400 cm-1 at spectral intervals of 2 cm-1. Elemental analyses of the substances were performed using a Thermo Scientific Flash 2000 CHNS analyzer. The compounds excitation/emission spectra were measured with a Perkin Elmer LS55 luminescence spectrometer.
Preparation of Sm(III) complexes
A solution of MPBP-1,3PPon (232 mg, 0.75 mmol), BMP-1,3PPon (213 mg, 0.75 mmol), BCP-1,3PPon (220 mg, 0.75 mmol) in dry ethanol (25 ml) was added dropwise into a solution of SmCl3 (64 mg, 0,25 mmol) in absolute ethanol (10 ml) under stirring at 75 °C for 5h. Then, the pH of the reaction mixture was adjusted to around 6 using NaOH (aq). The yellow powder was filtered off, washed with ethanol and dried in vacuo for 48 hours.
[Sm(MPBP-1,3PPon)3]·H2O (Fig. S1): Yield: 45%, mp: 245-248 °C, UV vis (DMF) λmax nm (log ε): 360 (1.697), 268 (0.825). IR ѵ ATR(cm-1): 3044 (br,C—H arm); 2956 (aliphaticcarbon); 1738 (str, C=O); 1595 (m, enolic C=C); 1251 (methoxy C-O-C); 504 (Sm—O). Chemical Formula: C60H65O10Sm; Molecular Weight: 1186,58; Anal.Calcd.For C60H65O10Sm (%): C, 65.72; H, 5.97. Found (%): C, 65.41; H, 5.65.
[Sm(BMP-1,3PPon)3]·2H2O (Fig. S2): Yield: 77%, mp: 238-241 °C, UV vis (DMF) λmax nm (log ε): 365 (2.102), 268 (0.959). IR ѵ ATR(cm-1): 3066 (br,C—H arm); 2958 (aliphaticcarbon); 1738 (str, C=O); 1597 (m, enolic C=C); 1255 (methoxy C-O-C); 465 (Sm—O). Chemical Formula: C51H49O14Sm; Molecular Weight: 1036,28; Anal.Calcd.For C51H49O14Sm (%): C, 59.11; H, 4.77. Found (%): C, 59.06; H, 4.34.
[Sm(BCP-1,3PPon)3]·H2O (Fig. S3): Yield: 41%, mp: 261-264 °C, UV vis (DMF) λmax nm (log ε): 358 (1.505), 268 (0.994). IR ѵ ATR(cm-1): 3069 (br,C—H arm); 2911 (aliphaticcarbon); 1737 (str, C=O); 1587 (m, enolic C=C); 483 (Sm—O). Chemical Formula: C45H29Cl6O7Sm; Molecular Weight: 1044,79; Anal.Calcd.For C45H29Cl6Sm (%): C, 51.73; H, 2.80. Found (%): C, 51.54; H, 2.71.
Cytotoxic Result:
The effects of [Sm(MPBP-1,3PPon)3]·H2O) and [Sm(BMP-1,3PPon)3]·2H2O on all concentrations (31, 62, 125, 250, 500 μM) were statistically significant when compared with DMSO in HTB-54 cells (p<0.001). [Sm(BCP-1,3PPon)3]·H2O complexes has no effect on cancer cells. For these reason, we were not studied on BEAS-2B for toxic experiment. Inhibitory concentrations of [Sm(MPBP-1,3PPon)3]·H2O) was determined as 11.05 μM in HTB-54 cells. Similarly [Sm(BMP-1,3PPon)3]·2H2O was 58.64 μM. So [Sm(MPBP-1,3PPon)3]·H2O) complex was better anti-cancer effect than [Sm(BMP-1,3PPon)3]·2H2O for cancer cells (Figure 2). In addition, [Sm(MPBP-1,3PPon)3]·H2O) complex has no toxic effect on healty cell (BEAS-2B) so this compound is more suitable for ideal drug properties and has potential therapeutic agent (Figure 3).
IR spectra
Within the range of 4000–400 cm-1, the IR spectra of compounds were determined. The IR spectrums of the [Sm(MPBP-1,3PPon)3]·H2O (Fig. S4), [Sm(BMP-1,3PPon)3]·2H2O (Fig. S5) and [Sm(BCP-1,3PPon)3]·H2O (Fig. S6) complexes showed a weak broad absorption bands at 3044, 3066 and 3069 cm-1 assigned to the aromatic carbon ѵ(C¾H) a stretching vibration [40], absorption bands at 2956, 2958 and 2911 cm-1 assigned to the aliphatic carbon ѵ(C¾H) a stretching vibration [41], respectively. The strong characteristic vibration bands of the lanthanide complexes occurring at 1738 and 1737 cm-1 are due to carbonyl ѵ(C=O) [42,43]. Also, the absorption bands observed at 1595, 1597 and 1587 cm-1 belong to the enolic carbon ѵ(C=C) a stretching vibration [44] and absorption bands at 1251 and 1255 cm-1 belong to the methoxy groups ѵ(C¾O¾C) a stretching vibration, respectively. The results show that ligands can effectively coordinate with the Sm(III) ion.
3.3. UV-Vis specta
The UV-Vis spectra of Sm(III) complexes were obtained in the range of 190-1100 nm by using DMF, DMSO and DCM solvents and the corresponding spectra are presented in Figure 4-6. These bands found in the UV-Vis spectra of Sm(III) complexes at 360, 365, and 358 nm in the DMF solution are linked to the singlet-singlet n- π* transition of enol groups. Furthermore, the π-π* transition of phenyl rings and carbonyl groups is ascribed to the absorption maxima at 268 nm. In DMSO, DMF, and DCM, the absorption wavelength of Sm(III) complexes was found to be slightly red shifted depending on the polarity of the solvent. [45-48].
Photoluminescence properties
The Sm(III) complexes of β-diketone derivatives showed a strong absorption band in the range of 300-410 nm due to the π-π* electronic transition of the conjugated β-diketone ligands. Therefore, we investigated the emission properties of the complexes in DMF (10−5 M) solution upon excitation at the maximum π-π* transition. The photoluminescence data are tabulated in Table 1. Emission spectra of [Sm(MPBP-1,3PPon)3]·H2O), [Sm(BMP-1,3PPon)3]·2H2O and [Sm(BCP-1,3PPon)3]·H2O are given in Figure 7. The ligands in the complexes [Sm(MPBP-1,3PPon)3]·H2O), [Sm(BMP-1,3PPon)3]·2H2O and [Sm(BCP-1,3PPon)3]·H2O are similar differing in the substitute groups on the pheny rings. The substitute groups did not cause considerable shifts in the excitation spectra of the complexes. In DMF, the complexes showed several emission bands in the range of 400-810 nm. All three complexes exhibited strong emission band in the range of 350-550 nm due to the ligand based emission 1S1 → 1S0. The substitute groups affect the ligand based emission maximums as well as intensities. The chloride groups has caused a considerable blue shift yet showed the highest emission intensity. This was observed for similar complexes reported by our group [40]. Complex [Sm(MPBP-1,3PPon)3]·H2O) shows Sm(III) based f-f transitions at 578, 586, 634, 729, 768 and 824 nm and these emission bands were assigned to f-f transition 4G5/2 → 6H5/2 (forbidden transition), 4G5/2 → 6H7/2 (magnetic dipole transition), 4G5/2 → 6H9/2 (electric-dipole transition), 4G5/2 → 6H11/2 (forbidden transition). The intensive emission band observed for electric-dipole transition (4G5/2 → 6H9/2) are associated with the coordination structures related to odd parity [49]. The coordination numbers and geometry around Sm(III) centre in those complexes are expected to be similar and the emission spectra due to the electric-dipole transition (4G5/2 → 6H9/2) are almost identical in all complexes. In the spectra of [Sm(BCP-1,3PPon)3]·H2O, 4G5/2 → 6H9/2 (electric-dipole transition) and 4G5/2 → 6H11/2 (forbidden transition) transitions were observed at 638 and 761 nm, respectively. The other f-f transitions were not observed.
Table 1. Photoluminescence data for the compounds.
Compound
|
Photoluminescence
|
Exc.
|
Em.
|
[Sm(MPBP-1,3PPon)3]·H2O)
|
308
|
426, 578, 586, 634, 729, 768, 824
|
[Sm(BMP-1,3PPon)3]·2H2O
|
310
|
424, 581, 639, 729, 756, 816
|
[Sm(BCP-1,3PPon)3]·H2O
|
310
|
408, 638, 761
|