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about twice as large as based on F, and R factors based on all data will be even larger. Non-hydrogen
atoms were refined with anisotropic thermal parameters. All of the hydrogen atoms in the MHBNB
structure could be located in the difference Fourier map. However, the hydrogen atoms were
geometrically relocated at chemically meaningful positions and were given riding model refinement. The
refinement data are listed in Table 1.
The MHBNB crystal structure belongs to a monoclinic and P21/n space group. The lattice cell parameters
are a=7.9566, b=21.3735, c=9.7681(Å) and the symmetry code of the molecule in the crystal unit is (i) x-
1/2, -y+1/2, z+3/2; (ii) x+1/2, -y+1/2, z-1/2; (iii) x+1, y, z-1; (v) x-1, y, z+1; The bond parameter such as
the bond length (Å), bond angle (°), dihedral angle (°) and hydrogen bonding interactions were measured.
This water also involves in hydrogen bonding interaction, but it does not change the symmetry, there was
observed a negligible influence due to the water present. The determined structure was optimized by
Density functional theory (DFT) calculation. The structure parameters were calculated and compared with
X-ray diffraction bond parameters, for example, the carbonyl (C=O) bond length has observed as about
1.229Å, whereas the calculated value is about 1.23Å. Similarly, the observed C=N (1.276Å), C-N
(1.337Å), C-O (1.367Å) and C-C in ring (~1.41 & ~1.37Å) bond lengths are matches well with the
computed bond parameters. The hydrogen bonding (HB) interactions have been observed like D-H,
H…A, D…A, and D-H…A. among the closest molecule, The donor nitrogen (N1-H2…O25ii) makes the
intermolecular hydrogen bonding with closest neighboring oxygen (O25ii) in hydroxybenzylidene (in ring
2), its D…A hydrogen bonding distance is about 3.078 Å and bonding angle is about 151̊ . Similarly, HB
at the terminal like C10-H11…O25i and C10-H11…O26ii is about 3.281 and 3.080 Å (D…A),
respectively, its corresponding angles are 154° and 129°(D-H…A). The determined crystal structure and
optimized gases phase structure are shown in Figure 1 (a-b). The comparison of experimental and
computed bond parameters are listed in Table S1 (Supporting information).
4.2 Vibrational analysis:
The vibrational analysis for MHBNB has carried out using FT-IR (4000-400 cm-1) and FT-Raman (3500-
50 cm-1) spectra (as shown in Figure 2a and Figure 2b). In addition to that, the DFT calculation was also
performed to explore the characteristic vibration in BCOP. The calculated wavenumbers were scaled
down by the appropriate scale factor [12] to bring closer with observed wavenumbers. This molecule
consists of 39 atoms and possesses 111 normal modes of vibrations but experimentally unable to observe
all those modes however the observed wavenumbers have compared with the simulated wavenumbers.
The hydroxyl (OH) stretching is very sensitive to hydrogen bonding and this vibration usually appears at
3500-3700cm-1 [13]. In the present investigation, the O-H stretching vibration appears at 3673 cm-1 as a
weak band, it indicates that there is no hydrogen bonding interaction at this OH (since the peak appeared