In crystals, adjacent Fe2+ and Ti4+ have a characteristic effect on this property. Heating alkali metal halides unusually changes this property by forming F-centers. A change in this property is produced by an equilibrium between a ring opening and closing at the oxygen (15[1])of a sultone or lactone in many triarylmethane compounds. Point defects in lattices that change this property are called this property’s namesake (*) centers. In many compounds, this property (-5[1])is caused by charge-transfer bands. Electronic (10[1])transitions between d orbitals confer this property to many coordination complexes of transition metals. A change in this property at the equivalence point marks the end of acid-base titration. For 10 points, name this property used to show the pH of a solution by indicators such as phenolphthalein. (10[1])■END■