( ( At ( ( neutral pH ) ( -LRB- ( ( pH 7 ) -RRB- ) ) ) ) ( , ( ( ( only ( the ( nitrogen atom ) ) ) ( of ( the ( diphenylamine moiety ) ) ) ) ( ( carries ( ( ( ( a ( positive charge ) ) and ) ( the ( blue ( dye molecule ) ) ) ) ( is ( ( an anion ) ( with ( ( an ( overall charge ) ) ( of -1 ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN At) (NP (NP (JJ neutral) (NN pH)) (PRN (-LRB- -LRB-) (NP (QP (CD pH) (CD 7))) (-RRB- -RRB-)))) (, ,) (NP (NP (RB only) (DT the) (NN nitrogen) (NN atom)) (PP (IN of) (NP (DT the) (JJ diphenylamine) (NN moiety)))) (VP (VBZ carries) (SBAR (S (NP (NP (DT a) (JJ positive) (NN charge)) (CC and) (NP (DT the) (JJ blue) (JJ dye) (NN molecule))) (VP (VBZ is) (NP (NP (DT an) (NN anion)) (PP (IN with) (NP (NP (DT an) (JJ overall) (NN charge)) (PP (IN of) (NP (CD -1)))))))))) (. .)))
At neutral pH (pH 7), only the nitrogen atom of the diphenylamine moiety carries a positive charge and the blue dye molecule is an anion with an overall charge of -1.
(ROOT (S (NP (NNS Atoms)) (VP (VBP carry) (NP (DT a) (JJ neutral) (NN charge))) (. .)))