Racemic mixtures and enantiomerically pure forms of novel 1-[(2′-substituted)-piperazin-1′-yl]-isoquinolines are norepinephrine (NE) transporter (NET) inhibitor compounds. Compounds of the invention are considered therapeutic agents for central nervous system (CNS) diseases and disorders, without limitation, including neurodegeneration, anxiety, depression, attention deficit disorders, drug dependency, and post traumatic stress disorder. Examples of the chemical syntheses of the compounds of the invention are provided. The isoquinoline compounds of the invention competitively bind at NET at nanomolar concentrations. The isoquinoline agents of the invention bind selectively to NET over other competitive transporter targets and receptor binding sites, including those of serotonin and dopamine, amongst others. The chemical syntheses of the invention are suitable for labeling with radionuclide atoms. Radiolabeled forms of the novel 1-[(2′-substituted)-piperazin-1′-yl]-isoquinoline compounds are positron emission tomography and single photon emission tomography imaging tracers. Methods of in vivo imaging with the tracers within various subjects and tissues therein, including regions of the brain, are provided. Imaging methods with the tracers in combination other NET inhibitor agents are provided. The imaging methods within subjects allow quantitative detection of NET, determinations of NET distributions, and measures of tracer interactions at NET in the presence or absence of non-radioactive NET agents. The tracer imaging methods are suitable to locate, diagnose, identify, evaluate, detect or quantitate NET, or abnormalities of NET, or NE abnormalities; that are associated with various CNS diseases and disorders.