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 (15[1])by an equilibrium between a ring opening and closing at the oxygen (15[1])of a sultone (15[1])or lactone in many triarylmethane compounds. Point defects in lattices that change this property are called (-5[1])this property’s namesake (*) centers. (-5[1])In many (-5[1])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 (10[3]-5[1])of transition (10[1])metals. (10[2])A change in this property at the equivalence point marks the end of (10[1])acid-base titration. (-5[1])For 10 points, name this property (10[1])used to show the pH of a solution by indicators such as phenolphthalein. (10[3])■END■ (10[3])