Manal Morad Karim - College of Dentistry, National University of Science and Technology, Dhi Qar, Iraq
Nada Othman Kattab - Department of Radiology & Sonar Techniques, Al-Noor University College, Nineveh, Iraq
Hala Bahir - Medical technical college, Al-Farahidi University, Iraq
Ayat Hussein Adhab - Department of Pharmacy, Al-Zahrawi University College, Karbala, Iraq
Azadeh Khanmohammadi - Department of Chemistry, Payame Noor University (PNU), P.O.Box ۱۹۳۹۵-۴۶۹۷, Tehran, Iran

The effects of non-covalent interactions on the strength and nature of the ۵-Aminosalicylic acid complexes and its thio analogous are investigated at the ωB۹۷XD/۶-۳۱۱++G(d,p) level of theory. The atoms in molecules and the natural bond orbital analyses are applied for a better understanding of these interactions. The results show that the cation-π interactions in the monovalent complexes have a stronger influence on the HB strength with respect to those in the divalent complexes. The replacement of oxygen by sulfur atoms increases the hydrogen bond strength in the complexes. Based on the molecular orbital data, the Li+ complexes with the larger energy gap are more stable and harder, while the Mg۲+ complexes with the lower energy gap are more reactive and thus softer.

Cation-π, Intramolecular hydrogen bond, DFT, aim, NBO