Carbon dots are among the new generation nanoscale materials that have gained demand in recent years and possess effective photoactive properties. A wide variety of effective surface passivation and modification methods are available for chemically functionalizing the surfaces of carbon quantum dots with various molecules. Carbon dots have a wide range of applications due to their properties such as high emission intensity, narrow fluorescence peaks, high water solubility, biocompatibility, and non-toxicity. Zr-containing UiO-66, a hybrid material class that has attracted considerable attention in recent years. In this study, a composite structure was created using carbon dots, which possess distinct superior properties, and UiO-66 cage. The interaction of N‑carbon dots/UiO-66 composites with heavy metal ions such as Fe(II), Zn(II), Pb(II), Ni(II), Hg(II), Co(II), Cr(III), Mn(II) and Ag(I) was investigated by changing their fluorescence intensity and sensitivity for Fe(II) ions was determined. Determination for Fe(II) ions could be carried out at the concentration level. N‑carbon dots synthesized using date seeds, considered biological waste, were combined with porous and regular UiO-66 for the first time using a green synthesis approach. This hybrid structure, unique in the literature, enabled precise optical determination of Fe(II) ions in standard solutions and a real drug using fluorescence spectroscopy. The measurement results were verified with two different methods such as UV–vis absorption and fluorescence spectroscopy, and the Fe(II) ion yield was found to be 1.993 μM and 5.83 μM, respectively.