Copper is an essential trace element for living organisms and has both known and additional suspected roles in human health and disease. The current understanding of copper metabolism is substantial but incomplete, particularly in regard to storage and exchange at the subcellular level, although available evidence indicates exchangeable intracellular copper is in the monovalent oxidation state. Selective fluorescent probes with sufficient sensitivity to detect Cu(I) availability at physiologically relevant levels and at subcellular resolution would be valuable tools for studying copper metabolism. As a contribution toward this goal, this work describes the development of Cu(I)-selective fluorescent probes with greatly improved aqueous solubility, contrast ratio, and fluorescence quantum yield. This work also describes the development of water-soluble, 1:1-binding chelators that form colorless, air-stable copper(I)-complexes. By acting as copper(I) buffering agents and affinity standards, these compounds can serve a complementary role to fluorescent probes in the study of copper biochemistry.