1. FORMATION OF CO-CRYSTAL AND CHARACTRIZATION OF ASPIRIN WITH CITRIC ACID AND PERCHLORIC ACID C.Muthuselvi.M.Sc.,M.Phil., Assistant Professor of Physics Devanga Arts College (Autonomous) Aruppukottai

2. Co-Crystals
Co-Crystals are crystalline materials composed of two or more molecules held together within the same crystal lattice.
Co-Crystals can be constructed
through the several types of
interaction, including hydrogen
bonding and van der walls
forces

3. Formation of Aspirin -Citric acid and Aspirin-Perchloric acid co-crystal
Slow evaporation method
Ethanol as a solvent
Colorless crystals obtained
The grown crystals are shown in figure

4. Characterization of Aspirin- Citric acid and Aspirin-Perchloric acid co-crystal
Powder XRD
FT-IR and Raman spectroscopy
UV-Visible Spectroscopy

5. Powder XRD
Crystalline quality of grown crystals were studied by powder diffraction analysis using a XPERT-PRO diffractometer with CuKα (1.540Å)in the 2Ɵ range .
S.No
2Ɵ (degree)
dspacing
(Å) 1.
10.63
8.309 2.
16.93
5.232 3.
27.65
3.222 4.
33.01
2.711
S.No 2Ɵ
(degree)
d spacing
(Å) 1.
5.42
16.295 2.
7.370
11.984 3.
10.573
8.360 4.
15.179
5.832

6. Powder XRD Pattern
The X-ray powder diffraction analysis revealed the formation of Co-crystals of Aspirin with citric acid and Perchloric acid in the crystalline form

7. FT-IR and Raman spectroscopy
The infrared and Raman spectroscopy studies are employed for the identification of the functional groups present in medically important drug namely Aspirin-citric acid and Aspirin-Perchloric acid co-crystal .
The FT-IR spectrum of Aspirin-citric acid and Aspirin-Perchloric acid co-crystal was recorded using SHIMADZU FT-IR spectrometer in the range cm-1.

8. The Raman spectrum of Aspirin-citric acid and Aspirin-Perchloric acid co-crystal was recorded using Princeton Acton SP-2500 Raman spectrometer in the range cm-1.
The observed Infrared and Raman spectra are illustrated in figure and the observed wave numbers of the various functional groups of title compound are tabulated.

9. FT-IR and Raman spectrum

10. Vibrational frequencies of Aspirin-citric acid Co-Crystal
IR ν(cm-1)
Raman ν(cm-1)
Assignment -
3240(s)
ν (OH)
3018(m)
3083(s)
ν(CH)
2870(w)
2833(w)
2940(s)
CH3.Str.
1755(s)
1689(br)
1605(s)
1604(s)
C=O.Str
1575(m)
1523(w)
C=C.Str.
1428(w)
CH2Sci.
1274(w)
C-OH.bending
665(s)
514(m)
424(m)
661(w)
428(m)
COO.Bending

11. Vibrational frequencies of Aspirin-Perchloric acid Co-Crystal
IR ν(cm-1)
Raman ν(cm-1)
Assignment
3236(s)
3231(w)
ν(OH) -
3061(w)
3086(m)
3055(m)
ν(CH)
3008(w)
2858(m)
1483(m)
1474(m)
CH3 .Str.
1747(w)
1658(w)
1632(s)
C=O.Str
1610(s)
1577(m)
1527(m)
1578(s)
C=C Str.
696(s)
657(s)
530(s)
462(s)
675(w)
527(w)
452(s)
ClO3 .Def.
567(s)
430(w)
569(s)
ClO4

12. The frequency assignments have been made for various functional groups
Due to the effect of hydrogen bonding the observed stretching modes and bending modes appear at slightly lower and higher wavenumbers respectively than those expected for free aspirin drug.
This study confirms the presence of both molecules in the co-crystal form due to the hydrogen bonding between them.

13. UV-Visible Spectroscopy
The optical transmittance and absorption spectrum of grown crystal has been recorded with SHIMADZU-UV 1601 double beam spectrometer in the range nm to find the suitability of crystal for optical applications.
The optical transmittance and absorption spectrum of grown crystals are shown in graphs

15. The crystal shows a good transmittance in the visible region .
From the absorption spectrum, there is no significant absorption in the entire range of visible light.
A good optical transmittance from ultraviolet to Infrared region is very useful for optical applications .

16. Conclusion
Co-crystallization technique was used to combine two drugs in a single solid phase and thus to achieve a newer approach for combination therapy.
Using the newer approach, Co-crystals of Aspirin with Citric acid and Aspirin with Perchloric acid were prepared in this work.

17. Synthesis of Co-Crystals of Aspirin – Citric acid and Aspirin-Perchloric acid were successfully carried out by slow evaporation method. Ethanol is the best solvent for the formation of co-crystals.
The X-ray powder diffraction analysis revealed the formation of Co-crystals of Aspirin with citric acid and Perchloric acid in the co-crystalline form.

18. The FT-IR and Raman spectra confirms the presence of both molecules and the frequency assignments of various functional groups explain the nature of hydrogen bonding between them.
The optical transparency was found out for each crystal by recording the UV-Visible spectrum. They show that the co-crystals have the optical transparency above 90% .

19. Thank you