Regulating crystal growth of ammonium dihydrogen phosphate through H-bonded additives

Herein, we report on the role of H-bonding in the growth of ammonium dihydrogen phosphate (ADP) crystals with additives like malic acid (MA), succinic acid (SA) and ascorbic acid (ASA). Pure and the additives doped ADP single crystals grown by natural evaporation method at room temperature are analysed for the intermolecular interactions and are examined by powder X-ray diffraction. The results confirm that the samples are single crystalline with additional planes due to additives in the solution. DSC thermograms for ADP and doped ADP crystals show that the additives increase the stability of the crystal and the latent heat of fusion (ΔH_f) of the samples depend inversely on the H-bond distances. Results from the FT-IR spectra indicate minimal influence of additives on the grown ADP crystal. Changes in the O–H–O hydrogen bond reflect the local environment. The additives show a marginal influence on the dipole moment values, with the doped ADP showing higher values than pure ADP. The NLO properties exhibit a reverse trend, with ADP + MA showing nearly seven times the value of pure ADP crystal. The enhanced stability and NLO property of the doped ADP compared with pure ADP demonstrate that the presence and strength of H-bonds play a key role in the overall structure of ADP.