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I recently stumbled across the substance "p,p′-terphenyldicarboxylic acid" in a scientific journal when recently reading about metal–organic frameworks.

Could someone explain the prefix p,p'- to me?

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  • $\begingroup$ Related to this is the $p,p'$ prefix for DDT, where we have two para chloro substituents on two different phenyl rings. $\endgroup$ – Gaurang Tandon Jan 10 '18 at 10:57
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I am guessing that this is the compound you are interested in:
p-Terphenyl-4,4′′-dicarboxylic acid
Sigma labels this compound as p-Terphenyl-4,4′′-dicarboxylic acid (or 1,4-Bis(4-carboxyphenyl)benzene).

In your case, the p,p' indicates that the 2 carboxylic acids are in the para positions on 2 of the phenyl rings.

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As LDC3 has pointed out, the two p stand for para. But taking into account that there are three different terphenyls, p,p'-terphenyldicarboxylic acid is ambiguous.

enter image description here

An unambiguous name would denote both the terphenyl core, as well as the positions of the $\ce{COOH}$ substituents on the outer rings, such as in p-terphenyl-4,4'-dicarboxylic acid.

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