Synthesis , Characterization , and Fluorescence Properties of Two New Heterocyclic Compounds Containing 1 , 5-Dioxaspiro Group

A precursor, C21H29NO8 (A1) was prepared by reactions of 1,1-dimethoxy-N,Ndimethylmethanamine and 1,5-dioxaspiro[5.5]undecane-2,4-dione. The new N-containing heterocyclic compound, C19H19NO4 (B1) was obtained by adding A1 into ethanol solution of o-toluidine. The crystal structure determination of two compounds were both found to belong to the triclinic P-1 space group. The precursor includes one (C2H8N) cation and one (C19H21O8) anion, which constituted a chained structure by N–H···O intraand intermolecular interactions. The title compound (B1) formed a 3D-network structure by weak C–H···O intermolecular interactions and π···π stacking interactions. The fluorescent behaviors of A1 and B1 in ethanol solution were discussed. The result shows that they exhibit blue and purplish blue emission, respectively.


Materials and Characterization
Elemental analyses were carried out on an Elementar Vario EL III elemental analyzer (Elementar, Hanau, Germany).IR data were determined on FT IR-650 spectrophotometer Nicolet Instrument Inc., Madison, WI, USA).NMR spectra were recorded on a Bruker Avance-500 spectrometer (Bruker, Elisabethhof, The Netherlands) with CD3COCD3 as the solvent.Photoluminescent (PL) spectra were recorded in a RF-5301PC spectrometer (Shimadzu, Kyoto, Japan).

Materials and Characterization
Elemental analyses were carried out on an Elementar Vario EL III elemental analyzer (Elementar, Hanau, Germany).IR data were determined on FT IR-650 spectrophotometer Nicolet Instrument Inc., Madison, WI, USA).NMR spectra were recorded on a Bruker Avance-500 spectrometer (Bruker, Elisabethhof, The Netherlands) with CD 3 COCD 3 as the solvent.Photoluminescent (PL) spectra were recorded in a RF-5301PC spectrometer (Shimadzu, Kyoto, Japan).

Crystal Data and Structure Refinement
Yellow and block crystals of A1 and B1 were mounted on Spider area detector.Their structures were solved and expanded by SHELXL-2015 and SHELXT-2015 [18].Crystallographic data of two compounds are listed in Table 1.The aromatic H atoms of A1 and B1 were refined with riding coordinates and the C-H distance is 0.93-0.97Å, the Uiso(H) values were set to 1.2 Ueq(C).However, the methyl H atoms of A1 were refined as rotating groups and the C-H distance is 0.96 Å, the Uiso(H) values were 1.5 Ueq(C).

Crystal Structure Determination of A1 and B1
As shown in Figure 1 and Table

Spectroscopic Properties of A1 and B1
In A1, the sharp peaks at 1703, 1686, 1246, 1212 cm −1 are due to the C=O and C-O vibrations of (C19 H21 O8) − anion, as shown in Figure 4.In B1, the sharp peaks at 1717, 1678, 1250, 1200 cm −1 are due to the C=O and C-O vibrations of C19 H19 N O4, which resembles to our earlier report [16,17].A similar peak at 1631 cm −1 and 1625 cm −1 is present, respectively, which indicting C=C stretching vibration of C( 8)=C(10)-C( 11) in (A1) and C( 8)=C(10)-N(1) (B1).The difference of the two compounds is that B1 exhibits sharp peaks at 1597 cm −1 (C=C), 1436 cm −1 (C-C), 752 cm −1 (νC−H of the phenyl ring.These facts were in accordance with the X-ray diffraction results The emission spectra of two compounds in dilute ethanol solution were discussed, as shown in Figure 5.The intermediate A1 exhibits bright blue emission with peak at 484 nm (Figure 6), while the excitation wavelength is at 239 nm.A sharp emission band of B1 was observed at 508 nm, when the excitation wavelength is at 252 nm.Its luminescent emission lies in the purplish blue region.In

Spectroscopic Properties of A1 and B1
In A1, the sharp peaks at 1703, 1686, 1246, 1212 cm −1 are due to the C=O and C-O vibrations of (C19 H21 O8) − anion, as shown in Figure 4.In B1, the sharp peaks at 1717, 1678, 1250, 1200 cm −1 are due to the C=O and C-O vibrations of C19 H19 N O4, which resembles to our earlier report [16,17].A similar peak at 1631 cm −1 and 1625 cm −1 is present, respectively, which indicting C=C stretching vibration of C( 8)=C(10)-C( 11) in (A1) and C( 8)=C(10)-N(1) (B1).The difference of the two compounds is that B1 exhibits sharp peaks at 1597 cm −1 (C=C), 1436 cm −1 (C-C), 752 cm −1 (νC−H of the phenyl ring.These facts were in accordance with the X-ray diffraction results The emission spectra of two compounds in dilute ethanol solution were discussed, as shown in Figure 5.The intermediate A1 exhibits bright blue emission with peak at 484 nm (Figure 6), while the excitation wavelength is at 239 nm.A sharp emission band of B1 was observed at 508 nm, when the excitation wavelength is at 252 nm.Its luminescent emission lies in the purplish blue region.In The emission spectra of two compounds in dilute ethanol solution were discussed, as shown in Figure 5.The intermediate A1 exhibits bright blue emission with peak at 484 nm (Figure 6), while the excitation wavelength is at 239 nm.A sharp emission band of B1 was observed at 508 nm, when the excitation wavelength is at 252 nm.Its luminescent emission lies in the purplish blue region.In addition, because of containing (o-tolylamino)methylene chromophore [19], the emission of B1 was red-shifted 24 nm than A1, and the relative intensity was increasing.These facts indicate that the two compounds are potential fluorescent materials.

Conflicts of Interest:
The authors declare no conflict of interest.

Figure 6 .
Figure 6.The color coordinates of A1 and B1.

Table 1 .
Crystallographic data and depository number for A1 and B1.
Crystals 2018, 8, x FOR PEER REVIEW 6 of 7 addition, because of containing (o-tolylamino)methylene chromophore [19], the emission of B1 was red-shifted 24 nm than A1, and the relative intensity was increasing.These facts indicate that the two compounds are potential fluorescent materials.