Studi sintesis ligan 2-(1,5-difenil-4,5-dihidro-1H-pirazol-3-yl)piridin sebagai fluorosensor ion logam berat Cu2+, Cd2+ dan Pb2+ = Study of synthesis ligand 2-(1,5-diphenyll-4,5-dihidro-1H-pyrazol-3-yl)pyridine as fluorosensor heavy metal ions Cu2+, Cd2+ and Pb2+ / Hastin Setiani