Just what the authors of the innovations report mean by acidic
water is not clear to me. To see one example of how the phrase
"acidic water molecules" is actually used by chemists, go to
http://www.rsc.org/ej/CC/2001/b103533a.pdf
Toward the end of the article you read:
"...When phenylboronic acid is then added to the
methanol solution water molecules present in the methanol
coordinate with the boron Lewis acid and become more
acidic. These more acidic water molecules can now
protonate compounds 1 and 3 as well as compound 2."
So, acidic water molecules are simply molecules of water
that can more easily give up a proton. Note that water is
not necessary to have an acid. An acid is a substance that can
take up an electron pair to form a covalent bond.
For example, boron trichloride (BF
3) is
an acid and combines with such bases as ammonia or ethyl ether.