The invention relates to new compounds of formula (1) wherein R is
hydrogen or a linear or branched C.sub.1-40alkyl; where X is O, S, or
NR.sup.1 where R.sup.1 is a hydrogen, a linear or branched C.sub.1-40
alkyl, C.sub.2-40 alkenyl or C.sub.2-40 alkynyl group, an aryl, a
heteroaryl or C.sub.1-40 alkylaryl or alkylheteroaryl group and where one
or both of C and D is OR.sup.2, SR.sup.2, NR.sup.3R.sup.4 where R.sup.2,
R.sup.3 and R.sup.4 are each independently hydrogen, a linear or branched
C.sub.1-40 alkyl, C.sub.2-40 alkenyl or C.sub.2-40 alkynyl group, an aryl
or C.sub.1-40 alkylaryl group or a linear or branched C.sub.1-40 alkyl
NR.sup.5R.sup.6 chain where R.sup.5 and R.sup.6 are each independently
hydrogen, a linear or branched C.sub.1-40 alkyl; or an optionally complex
metal ion M.sup.n+/n wherein n is an integer from 1 to 8; or where one or
both of C and D are amino acids or nucleic acids attached via either N, O
or S; and wherein m is an integer from 1 to 8; and wherein either: I) A
is a known aryl or heteroaryl fluorescent group and B is hydrogen, a
linear or branched C.sub.1-40 alkyl, C.sub.2-40 alkenyl or C.sub.2- 40
alkynyl group, an aryl, a heteroaryl or C.sub.1-40 alkylaryl or
alkylheteroaryl group or phosphonate P(O)(OR.sup.2).sub.2; II) B is a
known aryl or heteroaryl fluorescent group and A is hydrogen, a linear or
branched C.sub.1-40 alkyl, C.sub.2-40 alkenyl or C.sub.2-40 alkynyl
group, an aryl, a heteroaryl or C.sub.1-40 alkylaryl or alkylheteroaryl
group or a linear or branched C.sub.1-40 alkyl NR.sup.5R.sup.6 chain, or
a linear or branched C.sub.1-40 alkyl mono or di ester C.sub.1-40
alkylphosphonate or a linear or branched C.sub.1-40 alkylphosphonic acid;
III) Both A and B are known aryl or heteroaryl fluorescent groups. The
compounds are useful as fluorescent sensors for metal cations and have
the advantages of excellent water solubility, selectivity and sensitivity
to a variety of metal cations even in the presence of high concentrations
of Ca.sup.+2 Na.sup.+ and K.sup.+, good cell permeability, flexible and
simple syntheses, ease of attachment to polymers and bio-polymers to aid
the identification of both chemical and biological processes as well as
for assaying physiological samples and for the attachment to surfaces
such as glasses, ceramics and apatites. ##STR00001##
