intercalate

Intercalate is a verb meaning to insert or introduce something between layers or periods. In materials science and chemistry, intercalation describes the reversible insertion of molecules or ions into layered solids without significantly disturbing the host structure. Layered materials such as graphite, transition metal dichalcogenides, and clays can accommodate guest species between their sheets. Intercalation can modify properties including electrical conductivity, chemical reactivity, and storage capacity. A common example is lithium ions intercalating into graphite during charging and discharging of lithium-ion batteries. Intercalation compounds also appear in catalysis, electrochemistry, and energy storage, and are studied by spectroscopy and diffraction techniques.

In biology, intercalating agents insert between base pairs in double-stranded nucleic acids, often causing helix unwinding or distortion. This property is exploited for DNA staining in molecular biology, as well as for chemotherapy. Examples include ethidium bromide, acridines, and doxorubicin. Because intercalation can disrupt replication and transcription and may be mutagenic, these agents require careful handling and risk assessment.

In education, intercalation refers to taking a break during an undergraduate degree to study an additional subject or undertake research, typically leading to an intercalated degree. It is common in several university systems, notably in the United Kingdom, where students may extend the course by a year or more.

Etymology: from Latin intercalare, meaning to insert between; from inter- 'between' and calare 'to call, summon'.