complexed

1. 1
   verb

   Simple past and past participle of complex.

   The iron complexed with the chelating agent to form a stable ring structure.

   When the protein complexed with calcium, its overall shape changed sharply.

   Note

   A regular past form, built by adding -ed to a verb that chemists mostly use intransitively. One substance complexes with another, so the past form takes with and needs no object (the iron complexed with the chelating agent). The verb's rarer transitive meaning, "to complicate," would instead take a direct object. The same spelling also serves as the chemistry adjective, as in a complexed ion.

2. 2
   adjective

   Bonded with one or more other molecules or ions so as to exist as a single coordination compound.

   The complexed copper ion gives the solution a deep blue color.

   Only complexed forms of the nutrient can be absorbed by the plant's roots.

   Similarbound, chelated

   Oppositefree, uncomplexed, unbound

   Note

   A laboratory word that sorts a species by its state. It describes a metal ion held by surrounding ligands through coordinate bonds, as part of a coordination complex, rather than a free, uncoordinated ion. It usually sits before the noun (complexed copper, complexed iron) and is often set against free in contrasts. It grows from the verb's past participle: a complexed ion is one that has complexed.

3. 3
   adjectiveobsolete

   Made up of many interrelated parts; complicated or intricate.

   Note

   A dead end in the word's history: an adjective for "intricate" that wore a participle's -ed ending where modern English is content with plain complex. Thomas Browne writes of "complexed significations" in Pseudodoxia Epidemica, meaning compound ideas expressed by piecing images together. In this sense the form now looks like an error. Outside the chemistry adjective, write complex or complicated instead.

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