The colors of rubies and emeralds are so striking that they define shades of red and green—ruby red and emerald green. But ...

The last of these compounds shows an amazing property when hydrated. Its colour changes between pale green, dark green and violet depending on how many of the chromium ion's six coordination sites are ...

Both rubies and emeralds are minerals, which is a type of rock with a consistent chemical composition and a highly ordered ...

One feature of compounds made with transition metals is their intense colour. There are many examples in nature, including ...

Researchers have proposed using polymer membranes modified with copper, zinc, and chromium metal ions for water purification. These polymers were used for the first time in water purification via ...