Disclosed are crystalline free base ansolvate forms of 2-hydroxy-6-((2-(1-isopropyl-1H-pyrazol-5-yl)pyridin-3-yl)methoxy)benzaldehyde (or Compound 1), such as the free base Form I, Form II and Material N. Also disclosed are crystalline free base solvates of 2-hydroxy-6-((2-(1-isopropyl-1H-pyrazol-5-yl)pyridin-3-yl)methoxy)benzaldehyde (or Compound 1).本發明揭示2-羥基-6-((2-(1-異丙基-1H-吡唑-5-基)吡啶-3-基)甲氧基)苯甲醛(或化合物1)之結晶游離鹼非溶劑合物形式,諸如游離鹼形式I、形式II及材料N。本發明亦揭示2-羥基-6-((2-(1-異丙基-1H-吡唑-5-基)吡啶-3-基)甲氧基)苯甲醛(或化合物1)之結晶游離鹼溶劑合物。