The answer largely depends on the specific nature of your metal complexes. However, there are a few key aspects you can examine to better understand the cause of the cloudiness and sedimentation you're observing.

First, I would recommend checking the pH of your solution, as the stability and solubility of many metal complexes are highly pH-dependent. Aggregation might also be a factor to consider. It's possible that the chelating agents you're using are not polar enough, which could affect solubility.

You might also explore the use of surfactants or other solubilizing agents to improve dispersion. In my past work with metal complexes containing polycyclic aromatic hydrocarbons (such as pyrene and perylene), I found that forming inclusion complexes significantly enhanced their water solubility. This approach even allowed me to carry out catalysis directly in aqueous media.

I hope these suggestions are helpful for your system.

You can try adjusting the pH of the solution to improve solubility, as some complexes dissolve better at specific pH levels. You can also use small amounts of water miscible co-solvents like ethanol or DMSO. Heating or using sonication may help dissolve them more completely. Adding a small amount of a surfactant can also prevent sedimentation and cloudiness without changing the complex itself.

There are several strategies you can employ to improve the solubility of your metal chelated complexes and achieve a transparent solution. The slight cloudiness and sedimentation you're observing suggest that some of the complexes are forming aggregates or are simply not fully dissolving.

By systematically exploring these options, you should be able to identify the underlying cause of your solubility issues and achieve a stable, transparent aqueous solution of your metal chelated complexes.

This wouldn't be possible if you want pure metal complexes solutions. You need to add specific surfactants depending upon the nature of the metal ions, ligands and the metal complexes formed.

Thank you all, I tried, but the problem is still not rectified. I'm preparing Zinc HEDP complex. The solubility of the complex material was poor, and with higher pH, it would dissolve but would precipitate in hard water.